Explain Louis Sullivan’s functionalism as it relates to the Wainwright Building in St. Louis.

Louis Sullivan, best known for coining the phrase "form
follows function", a mantra popular in decorating and architectural circles, was
expressing one of the three components of what is called the "Vitruvian triad" in
architecture:  utilitas (convenience/utility/functionality), venustas (beauty and
aesthetics), and firmitas (the sturdiness or "firmness").  Although many designers and
architects approach the idea of functionality as being exclusive of aesthetics, and
assume Sullivan did as well, in fact the Chicago architect who helped design St. Louis's
Wainwright Building in the early 1890's, one of the world's first skyscrapers, was a
proponent of ornamentation as well, and did not find functionality and aesthetics to be
mutually exclusive.  Now on the National Register of Historic Places, the Wainwright
Building was build in a three part Italian palazzo style, consisting of a base, shaft
and attic; it was a modern variation of the classic column of the Greeks, and boasted a
wide frieze, a cornice of some depth, and decorative ornamention throughout the vertical
plane, including ornamented spandrels between the windows.