FABLE OF CUPID.
open and rarefy themselves, dilate and expand so as to occupy a greater space, and dispose them- selve> into a more extensive orbit; or, other hand, shut up and condense themselves, so as to retire irom the space they occupied and betake them selves to a narrower sphere. We must show, therefore, how far that influence hath its rise in heat and cold, and how far it dwells apart, and has a separate nature from that other influence. And that is certainly true, which Telesius affirms, that rarity and density are, as it were, the pecu liar works of heat and cold ; for the most essential requisite, in respect of these, is that the bodies should occupy a greater and a less space ; but yet these dogmas are received rather confusedly : for bodies seem sometimes to migrate from one natural site to another, and to transfer themselves, and that freely and, as it were, willingly, and changing their forms ; but sometimes they seem only driven from their natural site, and to return to their accustomed site, their old form remaining the same. And that progressive influence enter ing on a new site is commonly determined by heat and cold : but that other restorative influence is not so. For water expands itself into vapour and air, oil likewise, and fat substances, into steam and flame, by the power of heat, and, if they have completely transmigrated, do not return. Nay, even the air itself is dilated and extended by heat. But if the migration shall have been half full after the departure of heat, it easily falls back into itself; so as that there are also some properties of heat and cold in the restorative in fluence itself. But those which, without any intervening heat or violence, are extended and divided, even without any addition of cold or sub traction of heat, most readily are returned to their former sites when the force ceases, as in the blow ing of a glass egg, and in the emptying of bel lows. But that is far more evident in solid and dense bodies. For if cloth, or a string of an in strument be stretched, when the force is taken away, they leap back with great swiftness, and the same is the nature of compression. For the air, drawn together and confined with some vio lence, breaks forth with a considerable effort, and so the whole of tha4 mechanical motion by which a hard is struck by a hard body, which is com monly called the motion of force, through which solid bodies are discharged, and fly through the air or water, is nothing else than the contending of the parts of the discharged body* to free them selves from compression. And yet here are no traces of heat and cold. Nor can any one take occasion from Telesius to say, that a certain por tion of heat and cold is assigned to each natural site, according to a fixed analogy. And that it can thus happen, that though there be no addi tional heat or cold, yet if the space of the body of matter be extended or contracted, the thing would return to the same state, because more or less matter is laid on the sp. tee than is in proportion tn tin- lu-at or cold. Bat these, assertions, though not absolutely absurd, M-I-IH, m ertln-li->s, like tin; imaginations ot nun unwilling to %<> from their first opinions, and who do not follow reality and nature. For if heat and cold be aililed i.-. bodies thus extended or compressed, and that in a greater degree accords with the body itself, a-, if the stretched cloth be warmed at the lire, it ill not in any way make up for the thing, or extin guish the impetus of recovery. Ve have, then, made it plain that the influence of changing site does not depend, in a remarkable degree, upon heat and cold, when yet this is that very influence which assigns the greatest power to these prin ciples. Those two influences follow which are universally recognised, through which bodies seek masses or greater congregations of things conna tural with them, in observing of which, as of other subjects, men either trifle or err. For the vulgar school thinks it sufficient to have distinguished the natural from the forced motion, and to give out that heavy bodies are, by a natural motion, borne downward ; light, upward. But these speculations are of very little help to philosophy. For their " nature," " art," " force," are only terms of terms and trifles. They should refer this motion not only to nature, but should seek in this very motion the particular and proper bias and inclination of the natural body. For there are many other natural motions, according to very different passive natures of things from these. The subject, therefore, is to be laid down accord ing to these differences. Nay, those very motions which they call violent, are more truly natural than that which they call natural ; if that be more according to nature which is more powerful, or even which is more of a universal kind. For that motion of ascent and descent is not very potent, nor even universal, but as it were pro vincial, and for certain regions, and even yielding and subjected to other motions. Their saying that heavy bodies are borne downward, light, upward, is no more than saying that heavy are heavy, light, light bodies. For what is so predicated is assumed from the very force of the term in the subject. But if by heavy they mean dense, by light, rare, they do not advance the subject, only they lead it back rather to the adjunct and concomitant, than to the cause. But they who so explain the bias of heavy bodies as to assert that they are borne to the earth s centre, and light to the circumference and circuit of heaven, as to their proper destinations, certainly advance something, and hint at a cause, but yei with much inconsideration. For places are n v influences, nor is a body affected but by a In iiy. and every incitation of a body which seems to h seat itself, affects and endeavours a configuration toward another body, not collocation or simple >iu- A. T. R
