The shepherd. Moses who fed the flocks of Jethro, his father-in-law.
Sing, heavenly muse, that on the secret top Of Oreb or of Sinai didst inspire That shepherd, who first taught the chosen seed In the beginning how the heavens and earth Rose out of chaos.
N.B. Oreb, or Horeb and Sinai, are two heights of one mountain.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894