Kinght of the Art is a collection of artist biographies by Amy Steedman and has this passage:
It did not make much difference to us when we were little children whether our pictures were good or bad, as long as the colours were bright and we knew what they meant. But as we grow older and wiser our eyes grow wiser too, and we learn to know what is good and what is poor. Only, just as our tongues must be trained to speak, our hands to work, and our ears to love good music, so our eyes must be taught to see what is beautiful, or we may perhaps pass it carelessly by, and lose a great joy which might be ours.