I have met with nothing during the thirteen years since the foregoing was published that has given me any qualms about its soundness. From the point of view of the law courts and everyday life it is, of course, nonsense; but in the kingdom of thought, as in that of heaven, there are many mansions, and what would be extravagance in the cottage or farm-house, as it were, of daily practice, is but common decency in the palace of high philosophy, wherein dwells evolution. If we leave evolution alone, we may stick to common practice and the law courts; touch evolution and we are in another world; not higher, nor lower, but different as harmony from counterpoint. As, however, in the most absolute counterpoint there is still harmony, and in the most absolute harmony still counterpoint, so high philosophy should be still in touch with common sense, and common sense with high philosophy.
The common-sense view of the matter to people who are not over-curious and to whom time is money, will be that a baby is not a baby until it is born, and that when born it should be born in wedlock. Nevertheless, as a sop to high philosophy, every baby is allowed to be the offspring of its father and mother.
The high-philosophy view of the matter is that every human being is still but a fresh edition of the primordial cell with the latest additions and corrections; there has been no leap nor break in continuity anywhere; the man of to-day is the primordial cell of millions of years ago as truly as he is the himself of yesterday; he can only be denied to be the one on grounds that will prove him not to be the other. Everyone is both himself and all his direct ancestors and descendants as well; therefore, if we would be logical, he is one also with all his cousins, no matter how distant, for he and they are alike identical with the primordial cell, and we have already noted it as an axiom that things which are identical with the same are identical with one another. This is practically making him one with all living things, whether animal or vegetable, that ever have existed or ever will—something of all which may have been in the mind of Sophocles when he wrote:—
“Nor seest thou yet the gathering hosts of ill
That shall en-one thee both with thine own self
And with thine offspring.”
And all this has come of admitting that a man may be the same person for two days running! As for sopping common sense it will be enough to say that these remarks are to be taken in a strictly scientific sense, and have no appreciable importance as regards life and conduct. True they deal with the foundations on which all life and conduct are based, but like other foundations they are hidden out of sight, and the sounder they are, the less we trouble ourselves about them.
What other main common features between heredity and memory may we note besides the fact that neither can exist without that kind of physical continuity which we call personal identity? First, the development of the embryo proceeds in an established order; so must all habitual actions based on memory. Disturb the normal order and the performance is arrested. The better we know “God save the Queen,” the less easily can we play or sing it backwards. The return of memory again depends on the return of ideas associated with the particular thing that is remembered—we remember nothing but for the presence of these, and when enough of these are presented to us we remember everything. So, if the development of an embryo is due to memory, we should suppose the memory of the impregnate ovum to revert not to yesterday, when it was in the persons of its parents, but to the last occasion on which it was an impregnate ovum. The return of the old environment and the presence of old associations would at once involve recollection of the course that should be next taken, and the same should happen throughout the whole course of development. The actual course of development presents precisely the phenomena agreeable with this. For fuller treatment of this point I must refer the reader to the chapter on the abeyance of memory in my book Life and Habit, already referred to.
Secondly, we remember best our last few performances of any given kind, so our present performance will probably resemble some one or other of these; we remember our earlier performances by way of residuum only, but every now and then we revert to an earlier habit. This feature of memory is manifested in heredity by the way in which offspring commonly resembles most its nearer ancestors, but sometimes reverts to earlier ones. Brothers and sisters, each as it were giving their own version of the same story, but in different words, should generally resemble each other more closely than more distant relations. And this is what actually we find.
Thirdly, the introduction of slightly new elements into a method already established varies it beneficially; the new is soon fused with the old, and the monotony ceases to be oppressive. But if the new be too foreign, we cannot fuse the old and the new—nature seeming to hate equally too wide a deviation from ordinary practice and none at all. This fact reappears in heredity as the beneficial effects of occasional crossing on the one hand, and on the other, in the generally observed sterility of hybrids. If heredity be an affair of memory, how can an embryo, say of a mule, be expected to build up a mule on the strength of but two mule-memories? Hybridism causes a fault in the chain of memory, and it is to this cause that the usual sterility of hybrids must be referred.
Fourthly, it requires many repeated impressions to fix a method firmly, but when it has been engrained into us we cease to have much recollection of the manner in which it came to be so, or indeed of any individual repetition, but sometimes a single impression if prolonged as well as profound, produces a lasting impression and is liable to return with sudden force, and then to go on returning to us at intervals. As a general rule, however, abnormal impressions cannot long hold their own against the overwhelming preponderance of normal authority. This appears in heredity as the normal non-inheritance of mutilations on the one hand, and on the other as their occasional inheritance in the case of injuries followed by disease.
Fifthly, if heredity and memory are essentially the same, we should expect that no animal would develop new structures of importance after the age at which its species begins ordinarily to continue its race; for we cannot suppose offspring to remember anything that happens to the parent subsequently to the parent’s ceasing to contain the offspring within itself. From the average age, therefore, of reproduction, offspring should cease to have any further steady, continuous memory to fall back upon; what memory there is should be full of faults, and as such unreliable. An organism ought to develop as long as it is backed by memory—that is to say, until the average age at which reproduction begins; it should then continue to go for a time on the impetus already received, and should eventually decay through failure of any memory to support it, and tell it what to do. This corresponds absolutely with what we observe in organisms generally, and explains, on the one hand, why the age of puberty marks the beginning of completed development—a riddle hitherto not only unexplained but, so far as I have seen, unasked; it explains, on the other hand, the phenomena of old age—hitherto without even attempt at explanation.