This is an example of what you might call a prose poem. Prose poetry is a very loosely defined area of poetry -- essentially it is a poem written in prose form instead of verse form. Well why isn't it just prose then? Good question. Supposedly there are some lingering poetic qualities that mark it as prose poetry, but all of the good prose I read has scores of poetic qualities.
So prose poetry is difficult to define, but that doesn't change the fact that "A Part of the Forest" by Tomas Transtromer is a beautiful piece of writing. I sincerely hope you know a part of a forest somewhere like the one described in this poem. I think it's something that everyone needs.
A Part of the Forest
On the way there a pair of frightened wings clattered up, that was all. There you walk alone. It's a high building completely made of narrow cracks. A building that is always swaying but never falls. The thousandfold sun slips in through the cracks. In the play of light an inverted law of gravity prevails: the house is anchored in the sky, and everything that falls falls upward. You can turn around there. You can mourn there. There you dare look at certain old truths that otherwise are always kept packed away. The parts I play deep within float up there, hang like dried skulls in the ancestors' hut on some remote Melanesian island. An atmosphere of childhood around the spooky trophies. It's so mild in the forest.