Bird in Space
The Philadelphia Museum of Art
"I conceived it to be created in bronze and I made a plaster model of it. This I gave to the founder, together with the formula for the bronze alloy and other necessary indications. When the roughcast was delivered to me, I had to stop up the air holes and the core hole, to correct the various defects, and to polish the bronze with files and very fine emery. All this I did myself, by hand; this artistic finishing takes a very long time and is equivalent to beginning the whole work over again. I did not allow anybody else to do any of this finishing work, as the subject of the bronze was my own special creation and nobody but myself could have carried it out to my satisfaction."
More information can be found at http://en.wikipedia.org/wiki/Bird_in_Space.
Brancusi aimed to portray his most famous theme when it came to his sculptures -the true essence of things- when he created Bird in Space. Many of his other works also portray this style as well, such as Prometheus, The Newborn, and Sleeping Muse.