Discourse on virtue and they pass by in droves. Whistle and dance the shimmy, and you've got an audience. — Diogenes. 4th-century BC Greek Cynic philosopher
When two friends part they should lock up each other's secrets and exchange keys. The truly noble mind has no resentments.
As a matter of self-preservation, a man needs good friends or ardent enemies, for the former instruct him and the latter take him to task.