Ancient account of physician subspecialization

This is a follow-up to my recent post on Herodotus describing 6th-century BC Babylonians relying on "social networking" for health care.

In Book 2 of The Histories, Herodotus comments on Egyptian medicine (ca. 500 BC).  In opposition to Babylonian health care, Herodotus notes that in Egypt each physician just treats one illness.  He comments dryly that "Doctors are everywhere."

Hmmm.