«بِأَنْ أَغْشَى مَعَانَ الْأَدَبِ»
So that I might frequent the gathering places and sources of literary learning.
Aghshā means to visit or attend. Maʿān al-adab refers here to the places or gatherings where literature is cultivated; the image of a spring gives learning a sense of nourishment.
The narrator does more than hear about eloquent people. He approaches them and seeks firsthand conversation and experience.