This analysis, so obviously valid in any special field of thought in which one is aware of one’s ignorance, holds no less, it seems to me, for that universal ignorance in which all of us are born. If it does hold there, it may stand as one version of the hypothesis of human evolution--rational mind out of animal consciousness, man out of brute. The change that effected this evolution was not accomplished, however, once for all in some remote past. The outer device was transmissible, and hence became a racial characteristic. But the change itself must still be re-enacted in every growing child. Something of it is re-enacted in the emergence of every idea in the rational mind. How far it is carried and how complete the evolution depends upon deliberate cultivation. Intelligence is pure gift, the prior condition and animating agent of all thought. Whether intelligence itself may be increased by exercise is a matter of faith or doubt, as one chooses. In face of a primary mystery one can only be humble and dumb. But of that ingenious artifice, the arbitrary articulation of the consciousness into stable particles, there can be no doubt. It is a human invention in human hands. What can be done with these particles by way of thought depends in a given mind upon their range, the richness of their substance, their stability, and their clarity. And they can, with care, be extended, enriched, stabilised, clarified. That there are larger units, whole structures of thought, with which discipline may be occupied goes without saying. Not all the heritage of the civilised mind is deposited in these particles. But the larger units are themselves built of the smaller, and what any mind makes of them hangs on its prior possession of the elements of which they are built, and the quality of those elements. In childhood one may have read, say, _Gulliver_, or _Through the Looking Glass_, with delight, and in maturity may still read them with delight. The outer symbols are the same now as then, but the responsive thoughts are not. In response to each symbol now there rises richer substance than the mind then possessed, grounds for relationships which then escaped detection. The two, indeed--particle and structure--are inseparable in practice. It is in use that the particles have accumulated their substance and quality; it is by finding them in use that the mind identifies and enriches and clarifies them for itself. But it is they, I think--the ultimate premisses of all thought and the basis of all understanding--that lie at the bottom of the well into which discipline is poured.