A Treatise on Painting, by Leonardo da Vinci
Senex and Taylor, London
In order to retain the Air of any Man's Face, whom you chance to see, apply your self to the Study and Observation of the several different Faces which present themselves before you; always taking especial notice of those parts which distinguish one Man from another, and which contribute the most, towards that infinite and amazing variety so observable in the Species; these parts, are the Mouth, Eyes, Nose, Chin, Neck and Shoulders: The Nose, for instance, admits of ten different Shapes, and is either straight, crumpt, hollow, rais'd above, or below the middle, Aquiline, flat, sharp, or round; all which, appear with the greatest advantage when seen side-wise: Of Noses proper to be seen front-wise, there are twelve other kinds; even, big in the middle, small in the middle, big about the tip and small in the setting on, small at the tip and big at the setting on, Nostrils wide, narrow, tall, low, the Foramina open, or covered with the peak of the Nose. Thus every other part, how minute soever, will afford something particular for your Observation, all which being view'd with the necessary attention, will enable you afterwards to Design them from your Ideas. If this method be not altogether to your tast, you may observe that which follows: Carry always a little PocketBook with you, full of various Designs of the several parts just now mentioned; and when you find a necessity to retain any Man's Air, observe his Face very nicely, taking all his Features asunder, and considering them Piece-meal; remembring still as you go along to cast an Eye over your Collection, and to match the natural parts of the Face with the Artificial ones in the Book; putting a mark on such of the latter as come nearest the former; to be afterwards join'd together at your Lodgings.