Aristotle has now done with Practical and Constructive Science.^[1] He turns from Man with his disputations, reasonings, oratory, poetry, moral and social life, to the subjects of Speculative Science,—to Nature, the Universe, and God. In glancing at the series of great treatises in which the results of his thoughts and researches upon these subjects are embodied, it will be convenient to divide them under the three heads of Natural Philosophy, Biology, and Metaphysics. First, then, the ‘Physical Discourse,’ the treatise ‘On the Heavens,’ that 'On Generation and Destruction,’ and the ‘Meteorologies,’ form together a distinct whole,^[2] and contain the Natural Philosophy of Aristotle, of which let us now notice some of the salient points, leaving his Biology and Metaphysics to form the subject of future chapters.

Natural Philosophy, as conceived by Aristotle, was far more metaphysical than the science which is called by that name in the present day—a science based on ​Page:Aristotle (Grant).djvu/141 ​Page:Aristotle (Grant).djvu/142 ​Page:Aristotle (Grant).djvu/143 ​Page:Aristotle (Grant).djvu/144 ​Page:Aristotle (Grant).djvu/145 ​Page:Aristotle (Grant).djvu/146 ​Page:Aristotle (Grant).djvu/147 ​Page:Aristotle (Grant).djvu/148 ​Page:Aristotle (Grant).djvu/149 ​Page:Aristotle (Grant).djvu/150 ​Stagirite as an immense comet incessantly reproducing itself.”

Clearly, Aristotle’s contribution to Natural Philosophy did not consist in suggesting or leading the way to true views as to the nature and arrangement of the heavenly bodies. He not only was not in advance of his age in this respect, but was even behind it, in so far as he refused to adopt theories, which have since turned out to have been anticipations of the results of modern science. But, on the other hand, it must be remembered that those theories were incapable of verification at the time, and had no force in themselves to command the attention of the world. They were like the “false dawn” in tropical countries, which appears for a few minutes and then fades way, allowing the darkness again to reign supreme, till the true sunrise takes place. Unconvinced by the speculations of the Pythagorean school and of Aristarchus of Samos, the great Alexandrian astronomer, Ptolemy, in the second century of our era, reaffirmed the Aristotelian views as to the spherical form and motion of the heavens, as to the earth’s position in the centre of the heavens, and as to its being devoid of any motion of translation. And the Ptolemaic system satisfied men’s minds until, with Copernicus and Galileo, modern astronomy began.

We must allow that Aristotle’s cosmical ideas were erroneous and misleading. Still we must take them as constituting a mere fraction of his encyclopædia of philosophy, and we must recollect that they are put forth in works which laid out and constituted new sciences. ​Page:Aristotle (Grant).djvu/152 ​Page:Aristotle (Grant).djvu/153 ​Page:Aristotle (Grant).djvu/154 ​Chemistry is the black or Egyptian art, having taken its rise out of the searches made by the Alchemists to discover the philosopher's stone. Aristotle had no notion whatever of the rich field of knowledge and power which lay in the analysis of substances. He had no idea of the composition of water or air. The crucible and the retort had never been worked in Athens; the most superficial guess-work, as to what we should call the chemical properties of bodies, contented the philosophers of the day. Aristotle's work 'On Generation and Corruption' would have been the appropriate place for enunciating some of the laws of Chemistry; but he does not go beyond a resolution of the "Four Elements" into the ultimate principles of the Hot, the Cold, the Wet, and the Dry—the first pair being "active" and the second "passive" principles. Hot and Wet, we are told, form Air; Hot and Dry, Fire; Cold and Wet, Water; Cold and Dry, Earth. From these principles Aristotle deduces the generation and destruction of physical bodies; but on the details of a theory which now seems puerile we need not dwell.