Complex sentence: Ruskin argued that technical innovations in the architecture of the renaissance and the industrial revolution had subsumed its spiritual content and sapped its vitality and also that no new style was needed to redress this problem, the appropriate styles were already known to man.
Split into simpler sentences: Ruskin argued that technical innovations of architecture since the renaissance and particularly the industrial revolution, had subsumed its spiritual content and sapped its vitality. He also argued that no new style was needed to redress this problem, the appropriate styles were already known to man.