Keep away from people who try to belittle your ambitions. Small people always do that, but the really great make you feel that you, too, can become great.

Mark Twain (1835-1910) American writer [pseud. of Samuel Clemens]

(Attributed)

Quoted in Gay MacLaren, Morally We Roll Along (1938). A recollection of something Twain said to the author when she was a child. More information here.