The fact that psychology postulates an external material world and studies it in so far as it comes to be reflected in consciousness, points to another postulate which psychology must assume in addition, namely, the existence of an inner world consciousness.

— Boris Sidis The Foundations of Normal and Abnormal Psychology (1914)

More quotes by Boris Sidis

Nervous Ills their Cause and Cure (1922)

The Foundations of Normal and Abnormal Psychology (1914)

Philistine and Genius (1919)

Multiple Personality: an Experimental Investigation into Human Individuality (1904)

Nervous Ills their Cause and Cure (1922)

Quote text and notes from Wikiquote: Boris Sidis (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.