 The juxtaposition of smooth and irregular forms was an important principle, and is represented in "The Heart of the Andes" by the rounded hills and pool of water on the one hand, and by the contrasting jagged mountains and rough trees on the other.The theory of British critic John Ruskin was also an important influence on Church.Ruskin's "Modern Painters" was a five-volume treatise on art that was, according to American artist Worthington Whittredge, "in every landscape painter's hand" by mid-century.