He shall feed his flock like a shepherd: he shall gather the lambs with his arm, and carry them in his bosom, and shall gently lead those that are with young.
Read Chapter 40
Aponius
AD 500
I say that these [lambs] are the souls of those who are truly made heavenly philosophers, rejecting the world with its delights and false show and who prefer to dwell in the desert rather than in royal palaces. - "Exposition of Song of Songs 2.3"
He calls us lambs, the Spirit by the mouth of Isaiah is an unimpeachable witness, using the figurative appellation of lambs, which are still more tender than sheep, to express simplicity.