"as se'irim upon the herbage": as one who first begins to learn Torah. At first it falls upon him like a demon, viz. (Isaiah 13:21) "and se'irim will dance there."
Variantly: R. Bana'ah says: If you learn words of Torah for their own sake, they are "life" for you, as it is written (Proverbs 4:22) "For they are life to him who finds them, and to all of his flesh healing; and if not, they kill you, as it is written "My taking (i.e., Torah) ya'arof as the rain," arifah" being killing, viz. (Devarim 21:4) "And they shall break (ve'arfu) there the neck of the heifer in the river-bed." And it is written (Proverbs 7:26) "For she (Torah) has taken many lives; the number of its victims is legion."