With weary steps I loiter on, Tho' always under alter'd skies The purple from the distance dies, My prospect and horizon gone.
No joy the blowing season gives, The herald melodies of spring, But in the songs I love to sing A doubtful gleam of solace lives.
If any care for what is here Survive in spirits render'd free, Then are these songs I sing of thee Not all ungrateful to thine ear.
It's springtime now, but even that doesn't give Tennyson any joy. He's still hanging on and is kind of directionless—his "prospect" and "horizon" are gone. These are things that you look toward in setting a direction, and for him they are gone.
In his poems ("songs"), though, there's some hope for comfort. Perhaps if Arthur's spirit is out there somewhere, he's grateful for this elegy.
Except Tennyson expresses this in an understatement. His songs are "[n]ot all ungrateful" to Arthur's "ear," meaning—in a roundabout way—that his friend is grateful for the poem.