A friend should be one in whose understanding and virtue we can equally confide, and whose opinion we can value at once for its justness and its sincerity. Robert Hall
A friendship can weather most things and thrive in thin soil; but it needs a little mulch of letters and phone calls and small, silly presents every so often - just to save it from drying out completely. Pam Brown
If it's very painful for you to criticize your friends - you're safe in doing it. But if you take the slightest pleasure in it, that's the time to hold your tongue.