Not viewed laterally, but more or less obliquely. Thus, a man's leg lying on the ground, with the sole of the foot nearer the artist than the rest of the body, would be perspectively shortened.
“He forbids the fore-shortenings, because they make the parts appear little.” —Dryden.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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