163: Prenons deux groupes, l'un d'antécédents, l'autre de conséquents. On a lié tous les antécédents, moins un, à leurs conséquents, et tous les conséquents, moins un, à leurs antécédents. On peut conclure que l'antécédent qui reste est lié au conséquent qui reste. Par exemple, les physiciens, ayant calculé, d'après les lois de la propagation des ondes sonores, quelle doit être la vitesse du son, trouvèrent qu'en fait les sons vont plus vite que le calcul ne semble l'indiquer. Ce surplus ou résidu de vitesse est un conséquent et suppose un antécédent; Laplace trouva l'antécédent dans la chaleur que développe la condensation de chaque onde sonore, et cet élément nouveau introduit dans le calcul le rendit parfaitement exact. Voilà un exemple de la méthode des résidus. Sa règle est que «si l'on retranche d'un phénomène la partie qui est l'effet de certains antécédents, le résidu du phénomène est l'effet des antécédents qui restent.»

164: Prenons deux faits: la présence de la terre et l'oscillation du pendule, ou bien encore la présence de la lune et le mouvement des marées. Pour joindre directement ces deux phénomènes l'un à l'autre, il faudrait pouvoir supprimer le premier, et vérifier si cette suppression entraînerait l'absence du second. Or cette suppression est, dans l'un et l'autre de ces cas, matériellement impossible. Alors nous employons une voie indirecte pour joindre les deux phénomènes. Nous remarquons que toutes les variations de l'un correspondent à certaines variations de l'autre; que toutes les oscillations du pendule correspondent aux diverses positions de la terre; que toutes les circonstances des marées correspondent aux diverses positions de la lune. Nous en concluons que le second fait est l'antécédent du premier. Voilà un exemple de la méthode des variations concomitantes: sa règle fondamentale est que: «si un phénomène varie d'une façon quelconque toutes les fois qu'un autre phénomène varie d'une certaine façon, le premier est une cause ou un effet direct ou indirect du second.»

165: «La méthode de différence, dit Mill, a pour fondement, que tout ce qui ne saurait être éliminé est lié au phénomène par une loi. La méthode de concordance a pour fondement, que tout ce qui peut être éliminé n'est point lié au phénomène par une loi.» La méthode des résidus est un cas de la méthode de différence; la méthode des variations concomitantes en est un autre cas, avec cette distinction qu'elle opère, non sur les deux phénomènes, mais sur leurs variations.

166: We must separate dew from rain, and the moisture of fogs, and limit the application of the term to what is really meant, which is, the spontaneous appearance of moisture on substances exposed in the open air when no rain or visible wet is falling.

167: "Now, here we have analogous phenomena in the moisture which bedews a cold metal or stone when we breathe upon it; that which appears on a glass of water fresh from the well in hot weather; that which appears on the inside of windows when sudden rain or hail chills the external air; that which runs down our walls when, after a long frost, a warm moist thaw comes on." Comparing these cases, we find that they all contain the phenomenon which was proposed as the subject of investigation. Now "all these instances agree in one point, the coldness of the object dewed in comparison with the air in contact with it." But there still remains the most important case of all, that of nocturnal dew: does the same circumstance exist in this case? "Is it a fact that the object dewed is colder than the air? Certainly not, one would at first be inclined to say; for what is to make it so? But.... the experiment is easy; we have only to lay a thermometer in contact with the dewed substance, and hang one at a little distance above it, out of reach of its influence. The experiment has been therefore made; the question has been asked, and the answer has been invariably in the affirmative. Whenever an object contracts dew, it is colder than the air."

168: Here then is a complete application of the Method of Agreement, establishing the fact of an invariable connexion between the deposition of dew on a surface, and the coldness of that surface compared with the external air. But which of these is cause, and which effect? Or are they both effects of something else? On this subject the Method of Agreement can afford us no light: we must call in a more potent method. We must collect more facts, or, which comes to the same thing, vary the circumstances; since every instance in which the circumstances differ is a fresh fact: and especially, we must note the contrary or negative cases, i. e., where no dew is produced: for a comparison between instances of dew and instances of no dew is the condition necessary to bring the Method of Difference into play.

169: "Now, first, no dew is produced on the surface of polished metals, but it is very copiously on glass, both exposed with their faces upwards, and in some cases the under side of a horizontal plate of glass is also dewed." Here is an instance in which the effect is produced, and another instance in which it is not produced; but we cannot yet pronounce, as the canon of the Method of Difference requires, that the latter instance agrees with the former in all its circumstances except in one; for the differences between glass and polished metals are manifold, and the only thing we can as yet be sure of, is, that the cause of dew will be found among the circumstances by which the former substance is distinguished from the latter.

170: In the cases of polished metal and polished glass, the contrast shows evidently that the substance has much to do with the phenomenon; therefore let the substance alone be diversified as much as possible, by exposing polished surfaces of various kinds. This done, a scale of intensity becomes obvious. Those polished substances are found to be most strongly dewed which conduct heat worst, while those which conduct well, resist dew most effectually.

171: The conclusion obtained is, that, ceteris paribus, the deposition of dew is in some proportion to the power which the body possesses of resisting the passage of heat; and that this, therefore (or something connected with this), must be at least one of the causes which assist in producing the deposition of dew on the surface.

But if we expose rough surfaces instead of polished, we sometimes find this law interfered with. Thus, roughened iron, especially if painted over or blackened, becomes dewed sooner than varnished paper: the kind of surface, therefore, has a great influence. Expose, then, the same material in very diversified states as to surface (that is, employ the Method of Difference to ascertain concomitance of variations), "and another scale of intensity becomes at once apparent; those surfaces which part with their heat most readily by radiation, are found to contact dew most copiously."

172: The conclusion obtained by this new application of the method is, that, ceteris paribus, the deposition of dew is also in some proportion to the power of radiating heat; and that the quality of doing this abundantly (or some cause on which that quality depends) is another of the causes which promote the deposition of dew on the substance.

"Again, the influence ascertained to exist of substance and surface leads us to consider that of texture: and here, again, we are presented on trial with remarkable differences, and with a third scale of intensity, pointing out substances of a close firm texture, such as stones, metals, etc., as unfavourable, but those of a loose one, as cloth, velvet, wool, eiderdown, cotton, etc., as eminently favourable to the contraction of dew. The Method of Concomitant Variations is here, for the third time, had recourse to; and, as before, from necessity, since the texture of no substance is absolutely firm or absolutely loose. Looseness of texture, therefore, or something which is the cause of that quality, is another circumstance which promotes the deposition of dew; but this third cause resolves, itself into the first, viz. the quality of resisting the passage of heat: for substances of loose texture are precisely those which are best adapted for clothing or for impeding the free passage of heat from the skin into the air, so as to allow their outer surfaces to be very cold, while they remain warm within."

173: It thus appears that the instances in which much dew is deposited, which are very various, agree in this, and, so far as we are able to observe, in this only, that they either radiate heat rapidly or conduct it slowly: qualities between which there is no other circumstance of agreement, than that by virtue of either, the body tends to lose heat from the surface more rapidly than it can be restored from within. The instances, on the contrary, in which no dew, or but a small quantity of it, is formed, and which are also extremely various, agree (so far as we can observe) in nothing, except in not having this same property.

This doubt we are now able to resolve. We have found that, in every such instance, the substance must be one which, by its own properties or laws, would, if exposed in the night, become colder than the surrounding air. The coldness therefore, being accounted for independently of the dew, while it is proved that there is a connexion between the two, it must be the dew which depends on the coldness; or in other words, the coldness is the cause of the dew.

174: The law of causation, already so amply established, admits, however, of efficient additional corroboration in no less than three ways. First, by deduction from the known laws of aqueous vapour when diffused through air or any other gas; and though we have not yet come to the Deductive Method, we will not omit what is necessary to render the speculation complete. It is known by direct experiment that only a limited quantity of water can remain suspended in the state of vapour at each degree of temperature, and that this maximum grows less and less as the temperature diminishes. From this it follows, deductively, that if there is already as much vapour suspended as the air will contain at its existing temperature, any lowering of that temperature will cause a portion of the vapour to be condensed, and become water. But, again, we know deductively, from the laws of heat, that the contact of the air with a body colder than itself, will necessarily lower the temperature of the stratum of air immediately applied to its surface; and will therefore cause it to part with a portion of its water, which accordingly will, by the ordinary laws of gravitation or cohesion, attach itself to the surface of the body, thereby constituting dew. This deductive proof, it will have been seen, has the advantage of proving at once causation as well as coexistence; and it has the additional advantage that it also accounts for the exceptions to the occurrence of the phenomenon, the cases in which, although the body is colder than the air, yet no dew is deposited; by showing that this will necessarily be the case when the air is so undersupplied with aqueous vapour, comparatively to its temperature, that even when somewhat cooled by the contact of the colder body, it can still continue to hold in suspension all the vapour which was previously suspended in it: thus in a very dry summer there are no dews, in a very dry winter no hoar frost.

175: The second corroboration of the theory is by direct experiment, according to the canon of the Method of Difference. We can, by cooling the surface of any body, find in all cases some temperature (more or less inferior to that of the surrounding air, according to its hygrometric condition), at which dew will begin to be deposited. Here, too, therefore, the causation is directly proved. We can, it is true, accomplish this only on a small scale; but we have ample reason to conclude that the same operation, if conducted in Nature's great laboratory, would equally produce the effect.

And, finally, even on that great scale we are able to verify the result. The case is one of those rare cases; as we have shown them to be, in which nature works the experiment for us in the same manner in which we ourselves perform it; introducing into the previous state of things a single and perfectly definite new circumstance, and manifesting the effect so rapidly, that there is not time for any other material change in the preexisting circumstances. It is observed that dew is never copiously deposited in situations much screened from the open sky, and not at all in a cloudy night, but if the clouds withdraw even for a few minutes, and leave a clear opening, a deposition of dew presently begins, and goes on increasing.... Dew formed in clear intervals will often even evaporate again, when the sky becomes thickly overcast. The proof, therefore, is complete that the presence or absence of an uninterrupted communication with the sky causes the deposition or non-deposition of dew. Now, since a clear sky is nothing but the absence of clouds, and it is a known property of clouds, as of all other bodies between which and any given object nothing intervenes but an elastic fluid, that they tend to raise or keep up the superficial temperature of the object by radiating heat to it, we see at once that the disappearance of clouds will cause the surface to cool; so that Nature, in this case, produces a change in the antecedent by definite and known means, and the consequent follows accordingly: a natural experiment which satisfies the requisitions of the Method of Difference.

176: T. I, p. 500.

177: T. II, liv. VI, chap. IX. T. I, p. 487. Explication, d'après Liebig, de la décomposition, de la respiration, de l'empoisonnement, etc. Il y a un livre entier sur la méthode des sciences morales; je ne connais pas de meilleur traité sur ce sujet.

178: T. II, p. 4.

179: There exists in nature a number of permanent causes, which have subsisted ever since the human race has been in existence, and for an undefinite and probably an enormous length of time previous. The sun, the earth, and planets, with their various constituents, air, water, and the other distinguishable substances, whether simple or compound, of which nature is made up, are such Permanent Causes. They have existed, and the effects or consequences which they were fitted to produce have taken place (as often as the other conditions of the production met), from the very beginning of our experience. But we can give no account of the origin of the Permanent Causes themselves.

180: The resolution of the laws of the heavenly motions, established the previously unknown ultimate property of a mutual attraction between the bodies: the resolution, so far as it has yet proceeded, of the laws of crystallization, or chemical composition, electricity, magnetism, etc., points to various polarities, ultimately inherent in the particles of which bodies are composed; the comparative atomic weights of different kinds of bodies were ascertained by resolving, into more general laws, the uniformities observed in the proportions in which substances combine with one another; and so forth. Thus although every resolution of a complex uniformity into simpler and more elementary laws has an apparent tendency to diminish the number of the ultimate properties, and really does remove many properties from the list; yet (since the result of this simplifying process is to trace up an ever greater variety of different effects to the same agents), the further we advance in this direction, the greater number of distinct properties we are forced to recognise in one and the same object: the coexistences of which properties must accordingly be ranked among the ultimate generalities of nature.

181: Why these particular natural agents existed originally and no others, or why they are commingled in such and such proportions, and distributed in such a manner throughout space, is a question we cannot answer. More than this: we can discover nothing regular in the distribution itself; we can reduce it to no uniformity, to no law. There are no means by which, from the distribution of these causes or agents in one part of space, we could conjecture whether a similar distribution prevails in another.

182: I am convinced that any one accustomed to abstraction and analysis, who will fairly exert his faculties for the purpose, will, when his imagination has once learnt to entertain the notion, find no difficulty in conceiving that in some one for instance of the many firmaments into which sidereal astronomy now divides the universe, events may succeed one another at random, without any fixed law; nor can anything in our experience, or in our mental nature, constitute a sufficient, or indeed any reason for believing that this is nowhere the case. The grounds, therefore, which warrant us in rejecting such a supposition with respect to any of the phenomena of which we have experience, must be sought elsewhere than in any supposed necessity of our intellectual faculties.

183: In distant parts of the stellar regions, where the phenomena may be entirely unlike those with which we are acquainted, it would be folly to affirm confidently that this general law prevails, any more than those special ones which we have found to hold universally on our own planet. The uniformity in the succession of events, otherwise called the law of causation, must be received not as law of the universe, but of that portion of it only which is within the range of our means of sure observation, with a reasonable degree of extension to adjacent cases. To extend it further is to make a supposition without evidence, and to which, in the absence of any ground from experience for estimating its degree of probability, it would be idle to attempt to assign any.

184: Voyez les seconds analytiques, si supérieurs aux premiers: δί αἰτίων χαὶ προτέρων.

185: «Un fait, me disait un physicien éminent, est une superposition de lois.»

186: Die aufgehobene quantität.

187:

188:

Some blue peaks in the distance rose,
And white against the cold-white sky,
Shone out their crowning snows.
One willow over the river wept,
And shook the wave as the wind did sigh;
Above in the wind was the swallow,
Chasing himself at its own wild will,
And far thro' the marish green and still
The tangled water-courses slept,
Shot over with purple, and green, and yellow.

189: Nom de la plante donnée par Mercure à Ulysse.

190:

191: Voir the Pictures.

192:

193:

A million emeralds break from the ruby-budded lime
In the little grove where I sit—Ah, wherefore cannot I be
Like things of the season gay, like the bountiful season bland,
When the far-off sail is blown by the breeze of a softer clime,
Half-lost in the liquid azure bloom of a crescent of sea,
The silent sapphire-spangled marriage ring of the land?

194:

195:

And I stood on a giant deck and mix'd my breath
With a loyal people shouting a battle-cry....
Yet God's just doom shall be wreak'd on a giant liar,
And many a darkness into the light shall leap,
And shine in the sudden making of splendid names,
And noble thought be freer under the sun,
And the heart of a people beat with one desire;
For the long, long canker of peace is over and done,
And now by the side of the Black and the Baltic deep,
And deathful-grinning mouths of the fortress, flames
The blood-red blossom of war with a heart of fire.

196:

197:

And leaning there on those balusters, high
Above the empurpled champaign, drank the gale
That blown about the foliage underneath,
And sated with the innumerable rose,
Beat balm upon our eyelids.

198:

199:

A hubbub in the court of half the maids
Gather'd together; from the illumin'd hall
Long lanes of splendour slanted o'er a press
Of snowy shoulders, thick as herded ewes,
And rainbow robes, and gems and gemlike eyes,
And gold and golden heads; they to and fro
Fluctuated, as flowers in storm, some red, some pale,
All open-mouth'd, all gazing to the light,
Some crying there was an army in the land,
And some that men were in the very walls,
And some they cared not; till a clamour grew
As of a new-world Babel, woman-built
And worse-confounded: high above them stood
The placid marble Muses, looking peace.

200:

«You have done well and like a gentleman,
And like a prince: you have our thanks for all:
And you look well too in your woman's dress:
Well have you done and like a gentleman.
You have saved our life: we owe you bitter thanks:
Better have died and spilt our bones in the flood—
Then men had said—but now—what hinder me
To take such bloody vengeance on you both?—
Yet since our father—Wasps in the solemn hive,
You would-be quenchers of the light to be,
Barbarians, grosser than your native bears—
O would I had his sceptre for one hour!
You that have dared to break our bound, and gull'd
Our tutors, wrong'd and lied and thwarted us—
I wed with thee! I bound by precontract
Your bride, your bondslave! not tho' all the gold
That veins the world were pack'd to make your crown,
And every spoken tongue should lord you. Sir,
Your falsehood and your face are loathsome to us:
I trample on your offers and on you:
Begone! we will not look upon you more.
Here, push them out at gates.»

201:

From all a closer interest flourish'd up
Tenderness touch by touch, and last, to these,
Love, like an Alpine harebell hung with tears
By some cold morning glacier; frail at first
And feeble, all unconscious of itself,
But such as gather'd colour day by day.

202:

«If you be, what I think you, some sweet dream,
I would but ask you to fulfil yourself:
But if you be that Ida whom I know,
I ask you nothing: only, if a dream,
Sweet dream, be perfect. I shall die to-night.
Stoop down and seem to kiss me ere I die.»

203:

. . . . . . She turn'd; she paused;
She stoop'd; and with a great shock of the heart
Our mouths met: out of languor leapt a cry,
Crown'd Passion from the brinks of death, and up
Along the shuddering senses struck the soul,
And closed on fire with Ida's at the lips;
Till back I fell, and from mine arms she rose
Glowing all over noble shame; and all
Her falser self slipt from her like a robe,
And left her woman, lovelier in her mood
Than in her mould that other, when she come
From barren deeps to conquer all with love,
And down the streaming crystal dropt, and she
Far-fleeted by the purple island-sides,
Naked, a double light in air and wave....

204:

She murmur'd «Vain, in vain: it cannot be.
He will not love me: how then? must I die?»
Then as a little helpless innocent bird,
That has but one plain passage of fine notes,
Will sing the simple passage o'er and o'er
For all an april morning, till the ear
Wearies to hear it, so the simple maid
Went half the night repeating, «must I die?»

205:

At last she said «Sweet brothers, yester night
I seem'd a curious little maid again,
As happy as when we dwelt among the woods,
And when you used to take me with the flood
Up the great river in the boatman's boat.
Only you would not pass beyond the Cape
That has the poplar on it: there you fixt
Your limit, oft returning with the tide.
And yet I cried because you would not pass
Beyond it, and far up the shining flood
Until we found the palace of the king.
. . . . . . . . . . . . . .
. . . . . . Now shall I have my will.»

206:

But when the next sun brake from underground,
Then, those two brethren slowly with bent brows
Accompanying, the sad chariot-bier
Past like a shadow thro' the field, that shone
Full-summer, to that stream whereon the barge,
Pall'd all its length in blackest samite, lay.
There sat the life-long creature of the house,
Loyal, the dumb old servitor, on deck,
Winking his eyes, and twisted all his face.
So those two brethren from the chariot took
And on the black decks laid her in her bed,
Set in her hand a lily, o'er her hung
The silken case with braided blazonings
And kiss'd her quiet brows, and saying to her:
«Sister, farewell for ever,» and again
«Farewell, sweet sister,» parted all in tears.
Then rose the dumb old servitor, and the dead
Steer'd by the dumb went upward with the flood—
In her right hand the lily, in her left
The letter—all her bright hair streaming down—
And all the coverlid was cloth of gold
Drawn to her waist, and she herself in white
All but her face, and that clear-featured face
Was lovely, for she did not seem as dead
But fast asleep, and lay as tho' she smiled.

207:

"Most noble lord, sir Lancelot of the Lake,
I, sometime call'd the maid of Astolat,
Come, for you left me taking no farewell,
Hither, to take my last farewell of you.
I loved you, and my love had no return,
And therefore my true love has been my death.
And therefore to our lady Guinevere,
And to all other ladies, I make moan.
Pray for my soul, and yield me burial.
Pray for my soul thou too, sir Lancelot,
As thou art a knight peerless."

208:

A chapel nigh the field,
A broken chancel with a broken cross,
That stood on a dark strait of barren land.
On one side lay the ocean, and on one
Lay a great water, and the moon was full.

209:

The great brand
Made lightnings in the splendour of the moon,
And flashing round and round, and whirled in an arch,
Shot like streamer of the northern morn,
Seen where the moving isles of winter shock
By night, with noises of the northern sea.
So flash'd and fell the brand Excalibur:
But ere he dipt the surface, rose an arm
Clothed in white samite, mystic, wonderful,
And caught him by the hilt, and brandish'd him
Three times, and drew him under in the meer.

210:

They saw then how there hove a dusky barge
Dark as a funeral scarf from stern to stern,
Beneath them; and descending they were ware
That all the decks were dense with stately forms
Black-stoled, black-hooded, like a dream—by these
Three queens with crowns of gold. And from them rose
A cry that shiver'd to the tingling stars,
And, as it were one voice, an agony
Of lamentation like a wind, that shrills
All night in a waste land, where no one comes,
Or hath come, since the making of the world.

211:

Then murmur'd Arthur: "Place me in the barge,"
And to the barge they came. There those three queens
Put forth their hands, and took the king and wept.
But she that rose the tallest of them all
And fairest, laid his head in her lap,
And loosed the shatter'd casque, and chafed his hands
And call'd him by his name, complaining loud....

212:

The old order changeth, yielding place to the new,
And God fulfills himself in many ways,
Lest one good custom should corrupt the world....
If thou shouldst never see my face again
Pray for my soul. More things are wrought by prayer
That this world dreams of....
For so the whole round earth is every way
Bound by gold chains about the feet of God.
But now farewell. I am going a long way
With these thou seest,—if indeed I go—
(For all my mind is clouded with a doubt)
To the island-valley of Avilion,
Where falls not hall, or rain or any snow,
Nor ever wind blows loudly; but it lies
Deep-meadow'd, happy, fair with orchard-lawns
And bowery hollows crown'd with summer sea,
Where I will heal me of my grievous wound.

213:

Ô médiocrité! celui qui pour tout bien
T'apporte à ce tripot dégoûtant de la vie,
Est bien poltron au jeu s'il ne dit: Tout ou rien.