science and specialism are identical; not to specialize is to lose the prizes of life. Germany, which in philosophy and science does the original thinking of the world, is, as we all know, a nation of specialists.
There are, it is true, degrees of specialism, and the term is largely a relative one: in medicine, where the word is mostly used, and where until recently it has been a term of more or less reproach, all general practitioners are really specialists, since medicine and surgery are both offshoots from the professions of the priest and the barber; in biology, some are authorities only on paleontology, others on natural history in general, others on some special branch, as entomology, others still on some one insect, as the bee; and this subdivision is continually going on with the evolution of systematized knowledge. These statements may be truisms to students of sociology, but they are truisms that are forgotten by all the writers on testimony, although, as we shall see, they lie at the root of the reconstruction of the principles of evidence.
Equally important in its bearings on the scientific study of testimony is the recognition of the fact that memory is far more untrustworthy than has been commonly supposed. But a very small fraction of the impressions made on the cerebrum are so far retained as ever to be called up at will. Theoretically, the brain is like a target on which every idea that is evolved makes a permanent impression which no subsequent impressions can thoroughly destroy; practically, it is rather like a series of sieves by which thoughts are sifted through various stages below and on the borders of consciousness and recollection, while only the coarser and larger grains are retained where they can be used when needed. Under the stress of special excitements—as in the terror of drowning or protracted falling, or in trance, impressions long forgotten are revived and rise to temporary consciousness, so that men suppose that the panorama of all their past lives is passing before them; but, even under such exceptional crises, it is certain that only a comparatively few of our mental impressions actually reappear; some long-forgotten events arise with vivid distinctness, and the startled subject believes that all his life is let loose.
Nearly all the acquisitions and experiences of life are forgotten, even by the best memories; only the tiniest trifle of past events or past knowledge can ever be recalled. How dreams are forgotten we all know, but the difference between the recollection of sleeping and waking thoughts is only one of degree; by the standard of memory, all life is a dream. The pleasant experiences of infancy and early childhood, which, if they could be recalled at will, would so enrich and glorify human existence, are to us as though they had never been; as maturity appears, childhood dies.
Children really, as compared with adults, have very poor memories; they forget almost everything; even in infancy the experiences of each year are wiped out by the experiences of the succeeding year; bright