They then who affirm that there are certain irregular triangular figures in our body, and tell us also that shuddering, trembling, and quivering, and whatever else we suffer of the same nature, proceed from the roughness of those figures, if they mistake in the parts, nevertheless derive the beginning from whence they ought. For we ought to begin the question—as it were from Vesta—from the substance of all things. By which it chiefly appears wherein a philosopher differs from a physician, a husbandman, or a piper. For it is sufficient for these to contemplate the last causes. For if the consideration of the nearest causes of the affection go no farther than to find that the cause of a fever is intenseness of heat, or the lighting of some humor where it ought not to be, that the cause of blasting is the scorching heat of the sun after rain, and that the cause why pipes give a bass sound is the inclination of the pipes or the bringing them near one to another; this is enough for the artist to know in reference to his business. But when a philosopher for contemplation’s sake scrutinizes into the truth, the knowledge of remote causes is not the end but the beginning of his proceeding in search of the first and ultimate causes. Wherefore Plato and Democritus, enquiring after the cause of heat and gravity, did not stop at the consideration of earth and fire, but bringing things perceptible to sense to beginnings intelligible only by the mind, they went on even to the smallest, as it were the seeds of what they sought for. 9. But it is much the better way for us in the first place to move forward upon those things which are perceptible to sense, wherein Empedocles, Strato, and the Stoics placed the substances of active qualities; the Stoics ascribing primitive cold to the air, Empedocles and Strato to the water; and perhaps there might be somebody else who might affirm the earth to be the substance of cold. But first let us consider the opinions of those already named. Seeing then that fire is both hot and bright, therefore there must be something opposite to fire which is cold and dark. For as dark is opposite to light, so is cold to hot. Besides, as dark confounds the sight, so cold confounds the feeling. But heat diffuses the sense of feeling, as light diffuses the sense of seeing. Therefore that which is first dark in nature is first cold. Now that the air is first dark, was not unknown to the poets; for that they call the air darkness: The thickened air the fleet with darkness covered, Nor could the moonlight be from heaven discovered.[119] And again: Then darkness scattered and the fog dispelled, The sun brake forth, and all the fight beheld.[120]