Of natural philosophy there are two parts, the inquisition of causes and the production of effects; speculative and operative; natural science and natural prudence. Natural science is divided into physic and metaphysic. But since I have already defined a summary philosophy, and, again, a natural theology, both of which are commonly confounded with metaphysic, what is there remaining for metaphysic? This, that physic inquires concerning the material and efficient causes, but metaphysic handles the formal and final causes. So physic is in a middle term between natural history and metaphysic; for natural history describes the variety of things, physic the variable or respective causes, and metaphysic the fixed and constant causes. Of metaphysic I find that it is partly omitted and partly misplaced. In mathematics, which I place as a part of metaphysic, I can report no deficience. But natural prudence, or the operative part of natural philosophy, is very deficient. It were desirable that there should be a calendar or inventory made of all the inventions whereof man is possessed, with a note of useful things not yet invented. A calendar, also, of doubts, and another of popular errors, are to be desired.
We come now to the knowledge of ourselves—that is, to human philosophy or humanity. First, a general study of human nature will have regard to the sympathies and concordances between mind and body. Then, since the good of man’s body is of four kinds—health, beauty, strength, and pleasure—the knowledge of the body is also of four kinds—medicine, decoration or cosmetic, athletic, and the art voluptuary. Medicine has been more professed than laboured, and more laboured than advanced, the labour having been rather in circle than in progression.
As for human knowledge concerning the mind, it has two parts, one inquiring of the substance or nature of the soul, and the other of its faculties or functions. I believe that the first of these may be more soundly inquired than it has been, yet I hold that in the end it must be bounded by religion. It has two appendices, concerning divination and fascination; these have rather vapoured forth fables than kindled truth. The knowledge respecting the faculties of the mind is of two kinds, the one respecting understanding and reason, and the other respecting will, appetite, and affection, the imagination being active in both provinces. The intellectual arts are four—inquiry or invention, examination or judgment, custody or memory, and elocution or tradition; and these are severally divided into various sciences and arts. The knowledge of the appetite and will, or moral philosophy, leading to the culture and regiment of the mind, is very deficient.