The poem describes a man who is transported back to his childhood by listening to a piano being played. In three stanzas, it summarizes:
1) He recalls sitting under the piano as a child, watching his mother play with grace and beauty, feeling secure and warm.
2) The music overwhelms him with memories and nostalgia for Sunday evenings spent with his family in the comfort of their home.
3) He is overcome with emotion, weeping openly like a child for the lost innocence and security of his past. The powerful memories have destroyed his composure.