of embryology become for him, as Wolff, von Baer and Fritz Mû¥ller proclaimed, a record not only of the life-history of the individual but of the annals of its race. The facts of geographical distribution or even of the migration of birds lead on and on to speculations regarding lost continents, sunken islands, or bridges across ancient seas. Every nesting bird, every ant-hill or spiderãs web displays its psychological problems of instinct or intelligence. Above all, in things both great and small, the naturalist is rightfully impressed, and finally engrossed, by the peculiar beauty which is manifested in apparent fitness or ãadaptation,ããthe flower for the bee, the berry for the bird.
Time out of mind, it has been by way of the ãfinal cause,ã by the teleological concept of ãend,ã of ãpurpose,ã or of ãdesign,ã in one or another of its many forms (for its moods are many), that men have been chiefly wont to explain the phenomena of the living world; and it will be so while men have eyes to see and ears to hear withal. With Galen, as with Aristotle, it was the physicianãs way; with John Ray, as with Aristotle, it was the naturalistãs way; with Kant, as with Aristotle, it was the philosopherãs way. It was the old Hebrew way, and has its splendid setting in the story that God made ãevery plant of the field before it was in the earth, and every herb of the field before it grew.ã It is a common way, and a great way; for it brings with it a glimpse of a great vision, and it lies deep as the love of nature in the hearts of men.
Half overshadowing the ãefficientã or physical cause, the argument of the final cause appears in eighteenth century physics, in the hands of such men as Euler2 and Maupertuis, to whom Leibniz3 had passed it on. Half overshadowed by the mechanical concept, it runs through Claude Bernardãs LeûÏons sur les {4} phûˋnomû´nes de la Vie4, and abides in much of modern physiology5. Inherited from Hegel, it dominated Okenãs Naturphilosophie and lingered among his later disciples, who were wont to liken the course of organic evolution not to the straggling branches of a tree, but to the building of a temple, divinely planned, and the crowning of it with its polished minarets6.
It is retained, somewhat crudely, in modern embryology, by those who see in the early processes of growth a significance ãrather prospective than retrospective,ã such that the embryonic phenomena must be ãreferred directly to their usefulness in building the body of the future animal7ã:ãwhich is no more, and no less, than to say, with Aristotle, that the organism is the üöÙö£ö¢ü, or final cause, of its own processes of generation and development. It is writ large in that Entelechy8 which Driesch rediscovered, and which he made known to many who had neither learned of it from Aristotle, nor studied it with Leibniz, nor laughed at it with Voltaire. And, though it is in a very curious way, we are told that teleology was ãrefounded, reformed or rehabilitated9ã by Darwinãs theory of natural selection, whereby ãevery variety of form and colour was urgently and absolutely called upon to produce its title to existence either as an active useful agent, or as a survivalã of such active usefulness in the past. But in this last, and very important case, we have reached a ãteleologyã without a üöÙö£ö¢ü, {5} as men like Butler and Janet have been prompt to shew: a teleology in which the final cause becomes little more, if anything, than the mere expression or resultant of a process of sifting out of the good from the bad, or of the better from the worse, in short of a process of mechanism10. The apparent manifestations of ãpurposeã or adaptation become part of a mechanical philosophy, according to which ãchaque chose finit toujours par sãaccommoder û son milieu11.ã In short, by a road which resembles but is not the same as Maupertuisãs road, we find our way to the very world in which we are living, and find that if it be not, it is ever tending to become, ãthe best of all possible worlds12.ã
But the use of the teleological principle is but one way, not the whole or the only way, by which we may seek to learn how things came to be, and to take their places in the harmonious complexity of the world. To seek