Semper v. Le-Duc

Gottfried Semper, a German architect and architectural theorist born in Mecklenburg in 1803, and Eugène Viollet-le-Duc, a French architect and theorist born in Paris in 1814, were in many respects similar men.  Both were influenced by the writings of 19th century English social theorist John Ruskin, who wrote of the "Seven Lamps" of Architecture (sacrifice, truth, power, beauty, life, memory and obedience). Both praised the ancient Greek classical style of architecture.  Both were distinctly influenced by their European surroundings and heritage as well as by their military service.  Where they diverged was, in many facets, on the fundamental level of form versus function.
Viollet-le-Duc fundamentally believed that architecture should emphasize and largely represent the expression of its own construction.  His work revolved around finding the most efficient, or ideal, structural forms of materials and then designing constructs comprised from them.  He praised Greek architecture for its expression of structure while embracing modern materials to form the classical ideas into his vision of something that he believed to be perfect.  Credited as one of the fathers of the modern movement of architecture, Viollet-le-Duc is largely known, and often criticized, for his imaginative restorations of medieval French buildings in which he attempted to form them into his vision of their "ideal" form using the new materials available to him, a form that in many cases differed greatly from their original form.  His design style was free from the aesthetic cues of his surroundings as he attempted to find an ideal form and not an accepted cultural style.  The aesthetics of a construct, he believed, must clearly and prominently display its structural form. He focused his modernist ideas mostly on the gothic style of architecture, a style that Gottfried Semper saw as a reflection of the religious and aristocratic hierarchies and not the social values and context that he would come to focus on.
Semper, on the other hand, believed that function was above all else in the structure of space.  Structure need not be the supreme focus of architecture.  Rather, he believed that structure could be consolidated at points and not throughout the entire wall.  His theories stated that the roof and load bearing elements formed one system separate, and yet largely integrated into, a non load-bearing building envelope in a similar fashion to modern curtain walls. In his mind, structure and other building systems existed independently but could be, and should be, melded together into one based around fundamental concepts such as proportionality to achieve the desired prime social functions that he believed lie at the center of architecture.  This reflects his belief that at the center of built space, contained within "platform", "enclosure" and "roof," was a fundamentally social environment, his concept of "hearth." He praised Greek architecture for the social ideas which were expressed within.  Unlike Viollet-le-Duc, Semper believed that building aesthetics must reflect the socio-political conditions of their setting and place in time.  Architecture was not an expression of something ideal, but rather of the culture itself.