[29] Herein Harvey’s sagacity brought him towards the truth. “Air,” he says in the _De generatione_, “is given neither for the cooling nor the nutrition of animals ... it is as if heat were rather enkindled within the fœtus (at birth) than repressed by the influence of the air.” Boyle (who says that he worked under the influence of Harvey’s discoveries) carried this matter forward by most interesting and sagacious experiments with his air-pump. For the layman, I may add that (to speak generally) before Harvey’s time respiration was regarded not as a means of combustion but of refrigeration. How man became such a fiery dragon was the puzzle! [30] Perfection was attributed, not only by medieval philosophers but also by Plato and Aristotle, to the circle. Circular movement was therefore the most perfect, and therefore again must be that of the planets. This is a good illustration of the almost necessary tendency in the earlier excursions of thought to equate incoordinates, and to fill gaps in reasoning from alien sources. [31] Not only movement but also formative activity. The ἀρχὴ τῆς κινήσεως is the efficient cause of Aristotle; for him final causes direct motion—the οὗ ἕνεκα. Thus dialectic was taken for dynamics. Even Kant confused cause and effect with reason and consequence in hypothetical propositions (Benn). Caverni (Storia del methodo sperimentale in Italia, 1891-5) says that Jordanus Nemorarius (of Borgentreich near Warburg, d. 1236) made the great advance of extending the static physics of the ancients to establish dynamics; and that he introduced the word “moment.” In a cursory survey of the two works of Nemorarius which we have in Cambridge I have not been able to verify this statement; the notion I have found but not the word itself. [32] Vid. p. 44, note 2. [33] And Goethe: “Wie Himmelskräfte auf und nieder steigen Und sich die goldnen Eimer reichen! Mit segenduftenden Schwingen Vom Himmel durch die Erde dringen, Harmonisch all das All durchklingen.” Faust I. i. 1. In many of the older poets the same motive is found. Vaughan, a contemporary of Harvey, says: “And round beneath it Time in houres, dayes, yeares, Driven by the spheres Like a vast shadow moved.” The only celestial messenger who has discussed this matter with mankind was something of an obscurantist. Vid. Paradise Lost, Bk. VIII. [34] The word “philosophy” in the Middle Ages signified the pursuit of knowledge of things human and divine, and of the causes of them. It was often divided into Physics, Ethics and Logic. Cicero, to some of whose writings I have referred as then popular, says (in many passages, e.g. in the Acad. I. and II.) that philosophy “Prima rerum naturam scrutatur, secunda animum componit, tertia bene disserendi rationem docet.” [35] Vid. note, p. 77.