The fox has many tricks. The hedgehog has but one. But that is the best of all.

The fox has many tricks, and the hedgehog only one, but that is the best of all

A man is relieved and gay when he has put his heart into his work and done his best.

πόλλ' οἶδ' ἀλώπηξ, ἐχῖνος δ'ἓν μέγα

The fox knows many things - the hedgehog, one big one

You are doing your best only when you are trying to improve what you are doing