Section 143

XVII. (143) And as for the third argument, it is convicted by itself, as being derived only from an unsound system of questioning proceeding from the assertions originally made; for in truth it does not necessarily follow that a thing, all the parts of which are liable to corruption, is likewise perishable itself; but this is only inevitably true of that thing of which all the parts are perishable when taken collectively and together in the same place and at the same time, since in the case of a person who has the tip of his finger cut off, he is not disabled from living, but if he had the whole collection of all his parts and limbs cut off at once, he would die immediately. (144) Therefore in the same manner, if all the elements of the world together were all to disappear at one and the same moment, then it would be necessary to admit that the world was liable to corruption and destruction; but if each of these elements separately only changes its nature so as to assimilate to that of its nature, it is then rendered immortal rather than destroyed, according to the philosophical statement of the tragic poet--

"Nought that has once existed dies,

Though often what has been combined

Before, we separated find,

Invested with another form."