80 FABLE OF CUPID. 



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 entering on a new site is 

 commonly determined by heat and cgld: 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 influence itself. 

 But those which, without any intervening heat or violence, 

 are extended and divided, even without any addition of cold 

 or subtraction of heat, most readily are returned to their 

 former sites when the force ceases, as in the blowing of a 

 glass egg, and in the emptying of bellows. But that is far 

 more evident in solid and dense bodies. For if cloth, or a 

 string of an instrument 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 violence, breaks forth with a consi 

 derable effort, and so the whole of that 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 themselves from compression. And yet here 

 are no traces of heat and cold. Nor can any one take oc 

 casion from Telesius to say, that a certain portion 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 additional 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 space than is in proportion to the heat or cold. But 

 these assertions, though not absolutely absurd, seem, never 

 theless, like the imaginations of men unwilling to go from 

 their first opinions, and who do not follow reality and 

 nature. For if heat and cold be added to bodies thus ex- 



