John Ruskin (1873). “The Eagle's Nest: Ten Lectures on the Relation of Natural Science to Art, Given Before the University of Oxford in Lent Term, 1872”, p.80
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 (1873). “The Eagle's Nest: Ten Lectures on the Relation of Natural Science to Art, Given Before the University of Oxford in Lent Term, 1872”, p.34
John Ruskin “Two paths. Lectures on art, delivered before the University of Oxford in Hilary Term, 1870. Aratra Pentelici. Time and tide. Pre-Raphaelitism. The eagle's nest. King of the Golden River. The relation between Michael Angelo and Tintoret”
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