(Chapter 5) Footnote 14:

The optic nerves, called “the soft nerves of the eyes” by Galen, are classified in modern usage as the second pair of cranial nerves; Vesalius followed Galen and Mundinus in classifying the optic nerves as the first pair of cranial nerves. See J.P. Shaw, “ A History of the Enumeration of the Cranial Nerves by European and British Anatomists From the Time of Galen to 1895, with Comments on Nomenclature,” Clinical Anatomy 5 (1992), 466-484.