"Less Is More" and "God Is in the Details"
Mies summed up his philosophy in two lines. One is "less is more": strip away all excess and let the pure structure and space speak. The other is "God is in the details": precisely because there is no ornament, every joint, every edge, every proportion must be done to perfection, or simplicity sinks into crudeness. He proved that the hardest thing is not to add, but to subtract.