His great oeuvre still exerts a pervasive influence, both on architects as on the public. Hildebrand claims to have uncovered some deep motives that apply to most of Wrights houses which may explain why they are so extremely popular. He bases these motives on notions first identified and defined by Jay Appleton. Appleton noted that prospect and refuge are two conditions that have deep appeal to humans. Prospect means the potential of a site of offering a sight covering a considerable distance.
Refuge means the potential of providing a hiding-place.
Having both a sense for prospect and refuge aids in survival, when one is attracted to find places which enable to see but not to be seen. Following Appleton in this mode, Hildebrand founds architectural analysis on human cognition and psychology. Complexity meets man's desire for changing impulses, while order satisfies his need for recognizing regularities and commonalities. Hazard indicates a condition which might be threatening while mystery indicates a situation where other spaces are suggested but not revealed. The key to both Hildebrand and Appleton is, that these traits have been and are so fundamental for man's survival, that they are inherently structured in his genetic make-up.