In The Analysis of Mind, one of his most influential and exciting books, Russell presents an intriguing reconciliation of the materialism of psychology with the antimaterialism of physics. Bertrand Russell unfolds his ideas on consciousness, instinct and habit, desire and feeling, introspection, perception, sensations and images, memory, words and meaning, belief, and characteristics of mental phenomenon. Throughout, he explores the mystery of the mind, and proposes that there exists a fundamental material of which both mind and matter exist. "The stuff of which the world of our experience is composed is, in my belief, neither mind nor matter, but something more primitive than either." He wrote. "Both mind and matter seem to be composite, and the stuff of which they are compounded lies in a sense between the two, in a sense above them both, like a common ancestor." It remains one of the most important works on the philosophy of the mind.