De Anima [On the Soul]. One of the first western statements on psychology, and still influential. Full text on-line.

Mental Development in the Child and the Race. "Represents a pioneer effort to present a picture of the social nature of the self and the manner of its growth," by one of the founders of American psychology. Full text on-line.

A Treatise Concerning the Principles of Human Knowledge. An important work in the history of empiricism and idealism, and a string influence on David Hume. Full text on-line.

The Conscious Mind (Oxford Univ. Press, 1996). An interesting monograph on consciousness by a philosopher who believes that a materialistic reduction of consciousness is impossible.

Purple Perils. A collection of Gibson's private notes for seminars from 1954 to 1979, available on-line.

William H. Calvin's 1996 book on evolution of consciousness, intelligence, and language.

Joy of Visual Perception. An on-line book on the anatomy & physiology of vision, and on visual psychophysics.