Louis Sullivan said this quote

Form follows function.

~ Louis Sullivan

The building's identity resided in the ornament.

~ Louis Sullivan

Once you learn to look at architecture not merely as an art more or less well or more or less badly done, but as a social manifestation, the critical eye becomes clairvoyant.

~ Louis Sullivan

In the history of mankind there are recorded two great Inversions. The first, set forth by the Nazarene to the effect that love is a greater power and more real than vengeance. The second proclaimed the earth to be a sphere revolving in its course around the sun. These affirmations were made in the face of all evidence sacred to the contrary.

~ Louis Sullivan