On Painting: Show Muscles Only Where the Body Exerts Force
Restrained muscular definition keeps a figure from looking like a sack of nuts
A short painting precept written at the head of folio 128r, the rest of the page left blank. Leonardo warns against making every muscle of a figure evident: muscles gain prominence only where the limbs act in force or effort, while limbs at rest should show little muscular relief. A figure overloaded with muscles everywhere, he says, resembles a sack of nuts rather than a human body.
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Do not make every muscle of a figure evident
You should not make all the muscles of your figures evident, for even though they are in their places they show strongly only where the limbs are in great force or effort. Limbs that stay without exertion should be shown without display of muscles, or you will have imitated a sack of nuts rather than a human figure.