Name That Poet #8

This one is once again by a classic American Poet. Let's see who can remember this sonnet and its author:

The sun is set; and in his latest beams
Yon little cloud of ashen gray and gold,
Slowly upon the amber air unrolled,
The falling mantle of the Prophet seems.
From the dim headlands many a lighthouse gleams,
The street-lamps of the ocean; and behold,
O'erhead the banners of the night unfold;
The day hath passed into the land of dreams.
O summer day beside the joyous sea!
O summer day so wonderful and white,
So full of gladness and so full of pain!
Forever and forever shalt thou be
To some the gravestone of a dead delight,
To some the landmark of a new domain.

Congrats to Daniel! He answered correctly with Longfellow. And the poem title is "A Summer Day by the Sea". Thank you, Daniel.