A Treatise on Painting
by Leonardo da Vinci, translated by John Francis Rigaud
Of the Boundaries of Objects called Outlines or Contours
4004881A Treatise on Painting — Of the Boundaries of Objects called Outlines or ContoursJohn Francis RigaudLeonardo da Vinci

Chap. CXIV.Of the Boundaries of Objects called Outlines or Contours.

The outlines or contours of bodies are so little perceivable, that at any small distance between that and the object, the eye will not be able to recognise the features of a friend or relation, if it were not for their clothes and general appearance. So that by the knowledge of the whole it comes to know the parts.