Signs are often seen as elusive because they are. Symbols are often misunderstood because they are undefined. Derrida finds in Peirce one who sees both clear.
These mental signs are of mixed nature; the symbol parts of them are called concepts. If a man makes a new symbol, it is by thoughts involving concepts. So it is only out of symbols that a new symbol can grow.
Peirce complies with two apparently incompatible exigencies. The mistake here would be to sacrifice one for the other.
"Symbols grow. They come into being by development out of other signs, particularly from icons, or from mixed signs."