[59] but to fancy that any one has ever been born absolutely perfect is the part of those who are ignorant of the laws of nature, which are unchangeable ordinances. For our minds, being vitiated by the contagion of the mortal body which is united to them, are very naturally liable to changes and alterations, but the works of the nature of the universe are unalterable, since she has dominion over all things, and by means of the stability of whatever desires she has once established she preserves the definitions which have been originally fixed in an unchangeable state.