And one of the most important of all questions for morality and religion is the question, which of these two methods is valid.  If out of crass matter is evolved all animal and spiritual life, does that prove life to be nothing but matter; or does it not rather show that what we, in our ignorance, took to be mere matter was really something much greater?  If “crass matter” contains all this promise and potency, by what right do we still call it “crass”?  It is manifestly impossible to treat the potencies, assumed to lie in a thing that grows, as if they were of no significance; first, to assert that such potencies exist, in saying that the object develops; and then, to neglect them, and to regard the effect as constituted merely of its simplest elements.  Either these potencies are not in the object, or else the object has in it, and is, at the first, more than it appears to be.  Either the object does not grow, or the lowest stage of its being is no explanation of its true nature.

If we wish to know what the forms of natural life mean, we look in vain to their primary state.  We must watch the evolution and revelation of the secret hid in natural life, as it moves through the ascending cycles of the biological kingdom.  The idea of evolution, when it is not muddled, is synthetic—­not analytic; it explains the simplest in the light of the complex, the beginning in the light of the end, and not vice versa.  In a word, it follows the ways of nature, the footsteps of fact, instead of inventing a wilful backward path of its own.  And nature explains by gradually expanding.  If we hearken to nature, and not to the voice of illusory preconceptions, we shall hear her proclaim at the last stage, “Here is the meaning of the seedling.  Now it is clear what it really was; for the power which lay dormant has pushed itself into light, through bud and flower and leaf and fruit.”  The reality of a growing thing is its highest form of being.  The last explains the first, but not the first the last.  The first is abstract, incomplete, not yet actual, but mere potency; and we could never know even the potency, except in the light of its own actualization.

From this correction of the abstract view of development momentous consequences follow.  If the universe is, as science pronounces, an organic totality, which is ever converting its promise and potency into actuality, then we must add that the ultimate interpretation even of the lowest existence in the world cannot be given except on principles which are adequate to explain the highest.  We must “level up and not level down”:  we must not only deny that matter can explain spirit, but we must say that even matter itself cannot be fully understood, except as an element in a spiritual world."[A]

[Footnote A:  Professor Caird, The Critical Philosophy of Kant, p. 35.]