http://www.amazon.com/Nature-Order-Phenomenon-Environmental-...
Later in life he studied the organizing principles of nature and well-man-made artifacts and discussed the common patterns in his books "On the nature of order" [1]. The ideas are perhaps more grandiose than this author is discussing, but also very interesting when applied to engineering.
[1] http://www.amazon.com/Nature-Order-Phenomenon-Environmental-...
1. Levels of Scale 2. Strong Centers 3. Thick Boundaries 4. Alternating Repetition 5. Positive Space 6. Local Symmetry 7. Good Shape 8. Deep Interlock and Ambiguity 9. Gradients 10. Contrast 11. Echos 12. Roughness 13. The Void 14. Simplicity and Inner Calm 15. Each in the Other