2017 Reprint of 1925 Second Edition. Whitehead (1861-1947) was a prominent English mathematician and philosopher who co-authored the highly influential Principia Mathematica with Bertrand Russell. Originally published in 1919, and first republished in 1925 as this Second Edition, this work ranks among Whitehead's most important works; forming a perspective on scientific observation that incorporated a complex view of experience, rather than prioritizing the position of 'pure' sense data. Alongside companion volumes The Concept of Nature (1920) and The Principle of Relativity (1922), it created a framework for Whitehead's later metaphysical speculations. This is an important book that will be of value to anyone with an interest in the relationship between science and philosophy.