With which of these excerpts from Percy Shelley's "To a Skylark" does the speaker most directly express envy for the subject to work

This line "teach me half the gladness that thy brain must know" most directly express envy for the subject of the work.

Envy, in simple terms, is wanting to possess the quality or object which belongs to another. In this line, the speaker wants to be taught of the gladness, meaning that the speaker desires to have that attribute for himself/herself too.