It can be said that he applied his whole life, his tremendous intellect and his great spiritual faith to the concept of building up a philosophy that would reconcile Christian theology with the scientific theory of evolution, that would relate the facts of religious experience to those of natural science. The Phenomenon of Man is Pierre Teilhard's most important book and contains the quintessence of his thought. Its subject could be described as the surging evolution of the world from the primal stuff of the universe, through life, to consciousness and man.