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The sculptor must paint with his chisel; half his touches are not to realize, but to put power into, the form. They are touches of light and shadow, and raise a ridge, or sink a hollow, not to represent an actual ridge or hollow, but to get a line of light, or a spot of darkness.

John Ruskin (1866). “The seven lamps of architecture”, p.142
The sculptor must paint with his chisel; half his touches are not to realize, but to put power into, the form. They are touches of light and shadow, and raise a ridge, or sink a hollow, not to represent an actual ridge