But the success of our thinking depends upon which of these many aspects and relationships we observe and hence how we classify them. All aspects and relationships are equally true, as James said, if true at all. Correct thinking is the thinking which seizes upon those which are relevant to our interest and purpose. And the interest and purpose are human, not inherent in the world of things. Hence the order science finds in nature is not _given_; it is the order of human thought itself. Thus science also is “human letters.” The humanist, or organic, view of the world of science differentiates the twentieth century philosophy of nature from the mechanistic philosophy of earlier science. Mechanism, which is faith that the universe is reducible to Reason is, I hold, a survival from the old religious dualism, according to which matter and spirit were separate entities each belonging to its own world of phenomenon. The existence of Reason as an entity in itself could be taken for granted, because Reason belonged to the realm of spirit or mind, which though it existed outside the material order of being, had yet established this order in conformity to Reason. Huxley’s agnosticism properly denies that man can have knowledge of this world of spirit, yet retains from that realm the principle of reason which it re-discovers in the world of material phenomena. Hence Huxley was more religious than he knew. It is not the agnostic who is the non-religious man, but the naïve realist who sees every fact and situation uncolored by fancy or theory or illusion. For such a mind, spiritual values do not exist. This kind of materialism is a different thing from philosophical materialism, which is very theoretical and fanciful. There are persons who approach this naïve realism, but I doubt if anyone is wholly lacking in poetry and fancy. Certainly Huxley was not. Ordinarily we see our environment in a perspective of wish-fancy and traditional myth and magic. To more logical minds the world of objects is colored by the “sentiment of Rationality.” The universe appears to them to be governed, not by an indulgent or harsh imaginary Father, but by a principle of Reason. In each case, the fiction of security gives the feeling of salvation. In a wholly rational universe salvation is explanation. Everything is reasonable, hence right, if only we could explain it and show its place in the whole. Nineteenth century science could conceive of the world order as a mechanism and believe that it had passed from faith to knowledge in its agnosticism of the things of the spirit, but as Whitehead says, “the faith in the possibility of science generated antecedently to the development of modern scientific theory is an unconscious derivative from medieval theology.”