Quoted in the Architect Magazine's May 2012 article on Steven Holl:

‎"The real function of (Steven Holl's) watercolors, then, is to keep the lengthy design process - so full of puzzles and compromises - grounded in a visceral impulse. Holding a brush between the fingers and using the bristles to spread colored water on paper is a physical act that links even the most immense and technologically advanced structure to the architect's nerve endings" - Justin Davidson. 

And this bit of mystery: "Somehow, despite all the hands-off theorizing, he had developed a set of profound intuitions about how light clings to a ceiling or coats a wall, how enclosing a volume of air can endow it with sensual magic, and how soothing a touchable surface can be.  That emphasis on the immediate, physical experience of architecture - what Holl calls its 'phenomenology' - would seem at odd with his intellectual approach"

I love Holl's buildings so much.  I know we've had other threads on his watercolors, but I love how Davidson's article makes that simple connection between understanding one physical phenomena so well - colored water on paper - translating to understanding how light and color will act in dry space and how a body will respond to a surface.

Also, just because it's such a fun read: The Best Lecture Times by Steven Holl and Someone Else, by Orhan.