Having enumerated the six 'legitimate sources of pleasure in execution', Ruskin 'added a seventh - strangeness', illegitimate in itself but acceptable if combined with the others. He used the term to indicate the employment of an unusual, even surprising, method or technique. The effect of that technique is dependant on the ignorance of the viewer, and is thus illegitimate, yet at the same time can add greatly to his 'impression of the artist's knowledge' ( MP I:36). To exemplify, Ruskin described 'the execution of the bull's head' in The Adoration of the Magi by Rubens. The swiftly and thinly applied strokes cohere into a substantial form at the correct distance. As a foil, Ruskin introduced a similar head painted by Berchem in A Farrier and Peasants. For him, it offered 'no surprise, nor much pleasure of any kind'; neither did it succeed as intended.