Schinkel's aesthetic was not a crudely materialistic "truth to material" affair... but rather an attempt to inform iron and other industrial materials with an appropriate beauty through the direct collaboration of the artist in the manufacturing process.
Indifference to the fine arts comes close to barbarism.
Schinkel was not arbitrary in his use of historical modes but rather eclectic in the best sense of the word. He could search the past for its conspicuous successes using them both freely and discursively as the basis for a contemporary architecture.