I stumbled on this quote from Richard Le Gallienne today: "A critic is a man created to praise greater men than himself, but he is never able to find them."
When I Googled the words to find out more, I discovered this site, which lists a whole lot of amusing and insightful comments about critics. My favourites include:
"A critic is a legless man who teaches running." (Anonymous)
"A critic is someone who meddles with something that is none of his business." (Paul Gauguin)
"A drama critic is a person who surprises a playwright by informing him what he meant." (Wilson Mizner)
"A critic never fights the battle; they just go around shooting the wounded." (Tyne Daly)
"A drama critic is a man who leaves no turn unstoned." (George Bernard Shaw)
"A critic is a man who knows the way but can't drive the car." (Kenneth Tynan)
"The best critic needn't be right, just interesting." (Walter Kirn)
Finally on this topic, as visitors to my Theatre Reviews site will know, I am especially fond of this quote from British film critic Barry Norman: "I always knew that nobody's right and nobody's wrong in criticism. The only thing I could do was to make sure that whatever I said was what I really believed."