The line "Where are the songs of spring? Ay, where are they?" is from the poem "To Autumn" by John Keats, one of the major Romantic poets.
This poem reflects on the passage of time and the transition from the vitality of spring and summer to the ripeness and eventual decline of autumn. It's a meditation on beauty, change, and mortality.
The full stanza reads:
"Where are the songs of spring? Ay, where are they?
Think not of them, thou hast thy music too..."
This shows Keats embracing the beauty of autumn, even as it hints at the fading of life.