James Frederick Ferrier,
Berkeley and Idealism
(1883)
“ We answer that it is an image in which not one single minimum is in itself reversed, but in which all the minima are transposed merely in relation to one another. The inversion regards merely the relative position of the minima, and not the minima themselves. Thus, the upward part of each minimum in the object must also point upwards in the image on the retina. ”
