The instinct to which we make our ultimate appeal is in its first rise in the soul, crude, dim, and inarticulate. Gradually it shapes itself into greater clearness, aided, in the case of most men, by the myriad influences of religious thought and of historical tradition,--heightening and refining it when educed, but not creating it; separating the real gold from any spurious alloy it may have contracted. Like all our innate instincts this one is at first infantile, and, when it begins to assert itself, it prattles rather than speaks coherently. We do not here raise the general question of the existence of _à priori_ principles. We assume that the mind is not originally an _abrasa tabula_, but the endowments with which it starts are all gifts in embryo. They are not full-formed powers, so much as the capacities and potentialities of mental life. Their growth to maturity is most gradual, and the difference between their adult and their rudimentary phases is as wide as is the interval between a mature organization and the egg from which it springs. It is therefore no evidence against the reality or the trustworthiness of the intuition to which we appeal, that its manifestations are not uniform, or that it sometimes seems absent in the abnormal states of consciousness, or among the ruder civilizations of the world. We admit that it is difficult for the uninitiated to trace any affinity between its normal and its abnormal manifestations, when it is modified by circumstances to any extent. We farther admit that while never entirely absent, it may sometimes seem to slumber not only in stray individuals, but in a race or an era, and be transmitted from generation to generation in a latent state. It may hybernate, and then awake as from the sleep of years, arising against the will of its possessor and refusing to be silenced. Almost any phenomenon may call it forth, and no single phenomenon can quench it. It is the spontaneous utterance of the soul in presence of the object whose existence it attests, and as such it is necessarily prior to any act of reflection upon its character, validity, or significance. Reflex thought, which is the product of experience, cannot in any case originate an intuition, or account for those phenomena which we may call by that name, supposing them to be delusive. Nothing in us, from the simplest instinct to the loftiest intuition, could in any sense create the object it attests, or after which it seeks and feels. And all our ultimate principles, irreducible by analysis, simply attest and assert.