"In the pages to follow I shall not indulge in descriptions of persons--except when a facial expression, or a gesture, appears as a sign of a mute but eloquent language--because, as Boethius says, nothing is more fleeting than external form, which withers and alters like the flowers of the field at the appearance of autumn; and what would be the point of saying today that the abbot Abo had a stern eye and pale cheeks, when by now he and those around him are dust and their bodies have the mortal grayness of dust (only their souls, God grant, shining with a light that will never be extinguished)?
St. Andrew , c. 1326. Simone Martini. In the Metropolitan Museum of Art, New York.
But I would like to describe WIlliam at least once, because his singular features struck me, and it is characteristic of the young to become bound to an older and wiser man not only by the spell of his words and the sharpness of his mind, but also by the superficial form of his body, which proves very dear, like the figure of a father, whose gestures we study and whose frowns, whose smile we observe--without a shadow of lust to pollute this form (perhaps the only that is truly pure) of corporal love.
In the past, men were handsome and great (now they are children and dwarfs), but this is merely one of the many facts that demonstrate the disaster of an aging world." (14-15)
Eco, Umberto. The Name of the Rose. London: Picador, 1984 [Italy, 1980].
Why not describe people in words when it is so common to capture them in paintings, photographs, etc? Even if the nature is fleeting, the author/artist's subjective perspective will only be one of many understandings of the physical person. I like here how he spells it out for the reader...and then makes an immediate exception.