This aspect of the consonance is now quite familiar; but let us carefully note how completely dependent it is on natural selection. Mr. Herbert Spencer’s testimony is especially valuable, since he has always laid much stress on the hereditary transmission of acquired characters and still holds[183] “that the inheritance of functionally-caused alterations has played a larger part than Darwin admitted even at the close of his life; and that, coming more to the front as evolution has advanced, it has played the chief part in producing the highest types.” Now, in these types we certainly find a wide range of consonance between the psychological and the biological ends of behaviour; of which the phenomena of play may again be adduced as an example. Hence the special value of Mr. Herbert Spencer’s testimony to the part played by natural selection in establishing the consonance. “Only those races of beings,” he says, “_can have survived_ in which, on the average, agreeable feelings went along with activities conducive to life;” and again, “The most numerous _survivals_ must ever have been among races in which these adjustments of feelings to actions were the best.” The stress is here laid on the survival of those in which the consonance has obtained; the elimination of those in which it was absent: that is to say, on natural selection. And where else can it be laid? It is not the sort of thing which could be acquired. Suppose that, as we suggested above, an animal were born with a rooted hereditary aversion to everything nutritious and an inherited hunger for anything harmful and unfit for food. Under what conceivable conditions could such an animal acquire a complete change of its affective nature? Animals like things or they do not like them; only to a very limited extent, if at all, under natural conditions, can they learn to like them. We, indeed, can in some degree learn to take pleasure in that which at first, and by nature, is distasteful; but we do so by some external constraint, or from some motive of ideational origin. We put pressure upon ourselves, or have pressure put upon us, repeatedly to perform some irksome task; we fall into routine and custom; and the performance becomes so far second nature that its discontinuance produces an uncomfortable sense of something lacking in the daily round. Perhaps domestic animals learn to like the good offices we force them to perform for us. But here we have the element of external constraint, which is wholly, or almost wholly, absent under natural conditions. And there is no evidence that such acquired likings are inherited. That, however, is another question. Our present point is that, under nature, the conditions of such acquisition are lacking; so that, there being no acquisition, there is, in this case, nothing acquired to be transmitted.