A little knowledge is a dangerous thing (Prov.)

Che Iddio ci guardi da chi legge un libro solo (Prov.)

Meanings

People who have little knowledge, usually think that they are more expert than they really are

Origin

First used by Alexander Pope (1688 - 1744) in An Essay on Criticism, 1709: "A little learning is a dangerous thing; drink deep, or taste not the Pierian spring: there shallow draughts intoxicate the brain, and drinking largely sobers us again"