"For his view, his conviction was this: That the architectural art to be of contemporary immediate value must be plastic; all senseless conventional rigidity must be taken out of it; it must intelligently serve-it must not suppress. In this wise the forms under his hand would grow naturally out of the needs and express them frankly, and freshly. This meant in his courageous mind that he would put to the test a formula he had evolved, through long contemplation of living things, namely that form follows function, which would mean, in practice, that architecture might again become a living art, if this formula were but adhered to."

-Louis H. Sullivan,
The Autobiography of an Idea.
Dover Publications, Inc., New York., 1957 (Original Publisher: The American Institute of Architects, Inc. 1924), pp 257-258."