"Do not be critics, you people, I beg you. I was a critic and I wish I could take it all back because it came from a smelly and ignorant place in me, and spoke with a voice that was all rage and envy. Do not dismiss a book until you have written one, and do not dismiss a movie until you have made one, and do not dismiss a person until you have met them."
Dave Eggers. Love him or hate him, as you wish. As for me, I treasure this piece of advice for a host of reasons.