Detail of Great Argus Pheasant (Argusianus argus) zoo specimen, from SE Asia. Secondary wing feathers showing ocelli. Page 143 Vol II of Charles Darwin 'The Descent of Man and Selection in Relation to Sex' 1871. Darwin was fascinated by the detailed perfection of the Argus pheasant's ocelli spots which he considered were unique in resembling balls in sockets. On page 141 Vol II he notes 'That these ornaments should have been formed through the selection of many successive variations, not one of which was originally intended to produce the ball-and-socket effect, seems as incredible, as that one of Raphael's Madonnas should have been formed by the selection of chance daubs of paint made by a long succession of young artists, not one of whom intended at first to draw the human figure'.