OE exerise

Line 6-8 "Sing Heav'nly Muse, that on the secret top of Oreb, or of Sinai, didst inspire that sheperd, who first taught the chosen seed...

Sheperd:a. a man who guards, tends and herds
b. a spiritual guardian or pastor of a "flock"

Thinking of a sheperd as a man who tends to the sheep seemed to be irrelevant to this passage so that is why I decided to look it up. When I did, I found that it could also be a pastor or spiritual guardian. In the context of the line, this makes more sense. It also goes along with the words following..."who first taught the chosen seed." Since these were such religious times, a priest or pastor would be one of the first to teach you about things including the "chosen seed" which could be the birth of Christ and so forth.