Full Idea
We could not give names to things, if we had not a preliminary notion of what the things were.
Gist of Idea
To name something, you must already have an idea of what it is
Source
report of Epicurus (fragments/reports [c.289 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 10.21
Book Reference
Diogenes Laertius: 'Diogenes Laertius', ed/tr. Yonge,C.D. [Henry G. Bohn 1853], p.436