Henceforward consider your neighbor's character as a forbidden tree which you cannot touch. Be no less slow in praising yourself
than in censuring others, for the first indicates vanity and the second a want of charity. Speak of the virtues of your neighbor, but be silent as to his faults. Let nothing that you say lead others to think that he is naught but a man of virtue and honor. You will thus avoid innumerable sins and much remorse of conscience; you will be pleasing to God and men; and you will be respected by all as you respect others.
--Louis de Granada, The Sinner's Guide