What the summary of poem windmill by hwlongfellow?

There isn't a poem titled "Windmill" by Henry Wadsworth Longfellow. It's possible you're thinking of a different poem or author.

Could you please double-check the title and author? Perhaps you're thinking of a different poem about windmills, or maybe you're remembering the subject of a poem without the exact title.

If you can give me more information, I can help you find the poem and give you a summary.