LXI. I have remarked before, that if we are ignorant of what the elemental bodies consist, we cannot possibly know the nature of the mixtures. But even if we could ascertain what the elements are, we should still remain in profound philosophical ignorance with respect to the component parts, of both them and the mixtures; for admitting the four following, air, fire, water, and earth, to be elements of all the mixtures; who has yet ascertained the nature of those four bodies? Aristotle only reasoned upon their qualities, and this he did with so little precision, that all he said may be looked upon as doubtful, for he had no solid principle, from whence he inferred, that they possessed the properties which he attributed to them; but drew all his conclusions, from an ideal proportion which struck his own imagination; and respecting which, it has since been proved, that he was mistaken. He says that air is hot, and fire dry in the highest degree; but in our essay on physical paradoxes, we have proved that the air is not hot; and according to Aristotle’s definition of humidity, we may infer, that a flame is humid, for it cannot be contained within its own bounds, but pervades other regions. We also proved in our essay on physical paradoxes, that elemental fire is not hot in the highest degree; and to what I said there, I will add in this place, that experience shews us, one fire is hotter than another, and has greater power to heat or melt substances, either in consequence of its greater bulk, or on account of the matter with which it is made, or the manner the place is disposed and contrived, in which it is lighted; from all which it may be inferred, that fire in its nature is not hot in the highest degree, for if it was, as in every fire the nature of fire is preserved, every fire would be hot in the highest degree, and of course, could not be exceeded in heat by another fire.