The Commens Dictionary
Quote from ‘Lecture I [R]’
A conventional sign has since Aristotle and earlier received the name of symbol; but besides conventional symbols there are signs of the same nature except that instead of being based on express conventions they depend on natural dispositions. They are natural symbols. All thought takes place by means of natural symbols and of conventional symbols that have become naturalized. A symbol is employed over and over again, and we call all the occurrences of it occurrences of the same symbol. That is to say, it is the general type that makes the symbol, or its being made according to certain general precepts.