A key to Whitehead's Process and reality

Process and Reality is a book by Alfred North Whitehead, in which the author propounds a philosophy of organism, also called process philosophy. The book, published in 1929, is a revision of the Gifford Lectures he gave in 1927–28.

We diverge from Descartes by holding that what he has described as primary attributes of physical bodies, are really the forms of internal relationships between actual occasions. Such a change of thought is the shift from materialism to Organic Realism, as a basic idea of physical science.