THE EVOLUTION OF SCIENCE
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It has always been the tradition, with which one would not willingly break, that Harvey himself and his great dis- covery should be specially commemorated on this occasion. A long series of eminent men have so ably treated of the discovery of the circulation, and its consequences, that it would be difficult to add anything to what they have given us. But still I find that the genesis of Harvey’s idea, and more especially its historical connexion with the labours of the great men of antiquity who laid the foundations of anatomy and physiology, have not received the same degree of attention. Antecedents, however, no less than consequences, have to be taken into account in giving its true value to any scientific discovery.
It is generally admitted, though perhaps not always borne in mind, that no kind of knowledge has ever sprung into being without an antecedent, but is inseparably con- nected with what was known before. In this respect science is only like all other kinds of natural phenomena. The present aspect of the world, geologists tell us, is a necessary consequence of previous conditions and changes. The present races of animals and plants are the descendants of a long series whose origin we cannot trace. Modern civilization is the outcome of the efforts of man in all past ages to construct a social fabric. So even our modern science, which we sometimes speak of as though it were altogether a new thing, is only the final resultant of all the endeavours of men in past times to penetrate the secrets of nature. When we look back upon those strivings they often seem perverse and contradictory ; men at certain periods seem to have gone backward rather than forward ; we are struck less by the few grains of truth than by the great mass of what we call errors. But let us speak gently of these errors and call them rather imperfect truths, for, in science at least, the truth of to-day is error to-morrow. They are parts of a continuous evolution, in which the so-called truth and the so-called error are inseparably mingled.
Again, it seems to be sometimes thought that great original thinkers and discoverers make an exception to this
