John Ruskin, Louisa Caroline Tuthill (1860). “The True and the Beautiful in Nature, Art, Morals and Religion: Selected from the Works of John Ruskin...”, p.142
John Ruskin (188?). “Works: "A joy forever." The art of England. "Our fathers have told us." The laws of Fesole. The pleasures of England. Fiction fair and foul. Notes on the construction of sheepfolds. Inaugural address ... Cambridge School of Art, October 29th, 1858. The storm cloud of the nineteenth century. The opening of the Crystal Palace”
John Ruskin (1872). “The Political Economy of Art: Being the Substance (with Additions) of Two Lectures Delivered at Manchester, July 10th and 13th, 1857”, p.124