The surest way to corrupt a youth is to instruct him to hold in higher esteem those who think alike than those who think differently.

Friedrich Nietzsche (1844–1900) German philosopher and poet

The Dawn (1881)

Other translation:

The surest way of ruining a youth is to teach him to respect those who think as he does more highly than those who think differently from him.
[tr. Hollingdale (1982)]