The article reminded me of this quote, which I've heard in various forms:

"Do not despise my opinion, when I remind you that it should not hard for you to stop sometimes and look into the stains of walls, or the ashes of a fire, or clouds, or mud or like places, in which, if you consider them well, you may find really marvelous ideas. The mind of the painter is stimulated to new discoveries, the composition of battles of animals and men, various compositions of landscapes and monstrous things, such as devils and similar things, which may bring you honor, because by indistinct things the mind is stimulated to new inventions."

--Leonardo da Vinci