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

A man is relieved and gay when he has put his heart into his work and done his best; but what he has said or done otherwise shall give him no peace.

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

We do what we can, and then make up a theory to prove our performance the best.

We do what we must, and call it by the best names we can, and would fain have the praise of having intended the result which ensues.

Write it on your heart that every day is the best day in the year.