John Steinbeck said this quote

...You are a little boy. You want the moon to drink from as a golden cup; and so, it is very likely that you will become a great man -- if only you remain a little child. All the world'sgreat have been little boys who wanted the moon; running and climbing, they sometimes catch a firefly. But if one grow to a man's mind, that mind must see that it cannot have the moon and would not want it if it could -- and so, it catches no fireflies.' [Merlin]