Constance Jocelyn Ffoulkes, 1911 Encyclopædia Britannica, Volume 18… (1911)
“ If the drawing of the hand and ear were not always conspicuous, there were other peculiarities of this language of form to aid in the identification of a master: the treatment of the hair, as in Piero dei Franceschi; the indication of the sinews, as in Foppa; the drawing of the eye, as in Liberale da Verona; the modelling of the eyelid and upper lip, as in Ambrogio de Predis; the form of the feet, as in Luini. In short, all apparently insignificant details were of importance in his plan of study, for to him they were like the signature of the master. ”
