If you are in doubt whether to write a letter or not, don't. And the advice applies to many doubts in life besides that of letter writing.

In these days half our diseases come from neglect of the body in overwork of the brain.

And, of all the things upon earth, I hold that a faithful friend is the best.

You know There are moments when silence, prolonged and unbroken, More expressive may be than all words ever spoken.

Business dispatched is business well done, but business hurried is business ill done.

It is difficult to say who do you the most mischief, enemies with the worst intentions, or friends with the best.

There's no weapon that slays its victim so surely (if well aimed) as praise.