Louis Sullivan

The slogan is often reduced to a functionalist doctrine, but Sullivan's intent was far more complex. In his 1896 essay "The Tall Office Building Artistically Considered," he wrote: "It is the pervading law of all things organic and inorganic, of all things physical and metaphysical, of all things human and all things superhuman — that form ever follows function. This is the law."

For Sullivan, "function" encompassed not only practical use but spiritual expression. A building must fulfill its practical purpose while also communicating a higher order through form. This is why he insisted on ornament on skyscrapers — not applied decoration but the natural flowering of structural logic at the surface. The cast-iron ornament at Carson Pirie Scott's corner entrance — curling tendrils, interwoven geometries — is the peak of Sullivan's ornamental philosophy: they mark the entrance, guide the eye, and give a steel-frame building a face.

After 1900, Sullivan's career declined sharply. Chicago's taste turned toward Neoclassicism and historical styles; his organic ornament and modernist stance ceased to attract clients. His partnership with Adler ended in 1895, and major commissions dwindled. Yet it was in this marginal period that Sullivan produced two kinds of small masterpieces: a series of jewel-like banks across the Midwest, and a body of architectural-philosophical writings.

Sullivan's influence on Frank Lloyd Wright was profound. Wright worked in Sullivan's office for six years, called him "Lieber Meister" (Dear Master), and acknowledged throughout his life that his ideas on spatial flow and organic ornament came from Sullivan. Yet their fates diverged — Wright walked the long path of glory, while Sullivan spent his final years in poverty and alcohol. When he died in 1924 he was nearly forgotten, until modernist historians rediscovered his contribution and placed him as the irreplaceable origin in the genealogy of modern architecture.