“Only those who realize their own capacities and qualities are not affected by the opinions of others. Be careful, because those who praise are not entirely sincere. Those who criticize are mostly out of envy, jealousy and malice.”
Related quotes

The American Leviathan: The Republic in the Machine Age (1931) co-written with William Beard, p. 39
Context: If this statement by Judge Cooley is true, and the authority for it is unimpeachable, then the theory that the Constitution is a written document is a legal fiction. The idea that it can be understood by a study of its language and the history of its past development is equally mythical. It is what the Government and the people who count in public affairs recognize and respect as such, what they think it is. More than this. It is not merely what it has been, or what it is today. It is always becoming something else and those who criticize it and the acts done under it, as well as those who praise, help to make it what it will be tomorrow.

“Ellis was one of those people who constantly nag others to echo their own opinions.”
Source: Burmese Days (1934), Ch. II

“Those who can, build. Those who can't, criticize.”
Quoted in his obituary in the New York Times http://www.nytimes.com/learning/general/onthisday/bday/1218.html
“Quality is free, but only to those who are willing to pay heavily for it.”
Source: Peopleware: Productive Projects and Teams (1987), p. 23.

Original: In arte, chi ha buon gusto, possiede una qualità fondamentale durante la realizzazione di qualsiasi opera.
Source: prevale.net