We have seen that we cannot do anything thoroughly till we can do it unconsciously, and that we cannot do anything unconsciously till we can do it thoroughly; this at first seems illogical; but logic and consistency are luxuries for the gods, and the lower animals, only. Thus a boy cannot really know how to swim till he can swim, but he cannot swim till he knows how to swim. Conscious effort is but the process of rubbing off the rough corners from these two contradictory statements, till they eventually fit into one another so closely that it is impossible to disjoin them. Whenever, therefore, we see any creature able to go through any complicated and difficult process with little or no effort—whether it be a bird building her nest, or a hen’s egg making itself into a chicken, or an ovum turning itself into a baby—we may conclude that the creature has done the same thing on a very great number of past occasions. We found the phenomena exhibited by heredity to be so like those of memory, and to be so utterly inexplicable on any other supposition, that it was easier to suppose them due to memory in spite of the fact that we cannot remember having recollected, than to believe that because we cannot so remember, therefore the phenomena cannot be due to memory. We were thus led to consider “personal identity,” in order to see whether there was sufficient reason for denying that the experience, which we must have clearly gained somewhere, was gained by us when we were in the persons of our forefathers; we found, not without surprise, that unless we admitted that it might be so gained, in so far as that we once _actually were_ our remotest ancestor, we must change our ideas concerning personality altogether. We therefore assumed that the phenomena of heredity, whether as regards instinct or structure were mainly due to memory of past experiences, accumulated and fused till they had become automatic, or quasi automatic, much in the same way as after a long life— . . . “Old experience do attain To something like prophetic strain.” After dealing with certain phenomena of memory, but more especially with its abeyance and revival, we inquired what the principal corresponding phenomena of life and species should be, on the hypothesis that they were mainly due to memory. I think I may say that we found the hypothesis fit in with actual facts in a sufficiently satisfactory manner. We found not a few matters, as, for example, the sterility of hybrids, the phenomena of old age, and puberty as generally near the end of development, explain themselves with more completeness than I have yet heard of their being explained on any other hypothesis.