Great actions are seldom seen, but the labours of art are always at hand for those who desire to know what art has been able to perform.
 Samuel Johnson, The History of Rasselas, Prince of Abissinia (1759). copy citation

Context

“those who have kingdoms to govern have understandings to cultivate. “Example is always more efficacious than precept. A soldier is formed in war, and a painter must copy pictures. In this, contemplative life has the advantage. Great actions are seldom seen, but the labours of art are always at hand for those who desire to know what art has been able to perform. “When the eye or the imagination is struck with any uncommon work, the next transition of an active mind is to the means by which it was performed. Here begins the true use of such contemplation. We enlarge our comprehension by new ideas, and perhaps recover some art lost to mankind, or learn what is less perfectly known in our own country.” source