This compendium presents psychology as an empirical science of immediate experience, outlining methods of observation and experiment and situating psychological inquiry among natural and human sciences. It analyzes mental life from elemental sensations and feelings through higher syntheses such as perception, attention, memory, association, emotion, and volition, and surveys causal laws governing mental processes and development. Sections address experimental techniques, the physiological basis and methodological limits of psychological study, and broader topics including social and language-related phenomena. The text gives a systematic, concise overview of central theories, competing approaches, and key findings for students and general readers.