Page:1888 Cicero's Tusculan Disputations.djvu/271

Rh to its natural state, if it were not that, when heat is applied to it, it again becomes liquefied and dissolved, and so diffuses itself. Therefore, by northern and other cold winds it is frozen and hardened, and in turn it dissolves and melts again by heat. The seas likewise, we find, when agitated by winds, grow warm, so that from this fact we may understand that there is heat included in that vast body of water; for we cannot imagine it to be external and adventitious heat, but such as is stirred up by agitation from the deep recesses of the seas; and the same thing takes place with respect to our bodies, which grow warm with motion and exercise.

And the very air itself, which indeed is the coldest element, is by no means void of heat; for there is a great quantity, arising from the exhalations of water, which appears to be a sort of steam occasioned by its internal heat, like that of boiling liquors. The fourth part of the universe is entirely fire, and is the source of the salutary and vital heat which is found in the rest. From hence we may conclude that, as all parts of the world are sustained by heat, the world itself also has such a great length of time subsisted from the same cause; and so much the more, because we ought to understand that that hot and fiery principle is so diffused over universal nature that there is contained in it a power and cause of generation and procreation, from which all animate beings, and all those creatures of the vegetable world, the roots of which are contained in the earth, must inevitably derive their origin and their increase.

XI. It is nature, consequently, that continues and preserves the world, and that, too, a nature which is not destitute of sense and reason; for in every essence that is not simple, but composed of several parts, there must be some predominant quality—as, for instance, the mind in man, and in beasts something resembling it, from which arise all the appetites and desires for anything. As for trees, and all the vegetable produce of the earth, it is thought to be in their roots. I call that the predominant quality, which