Responding to Principle 5.4: Bodies Matter!, I used to read a ton of Kung-Fu novels (修仙小说) in middle school, in which all the character can examine the ‘meridians’ (经络) within their body experience it as an object. With clear view of what we are doing with the body, the mental model of performing any task could be laid out straight. However, I belive the mental models are oversimplified models of what we sense when performing an instrument. From my own experinece as a violinist, my playing is heavily effected by fragments popping out of my memory my current mood, to the extent that I don't actually feel my fingers or where I'm at in a given piece. So when I read about Ben Kenapp and Atau Tanaka's use of involuntary and semi-voluntary human bio-signals for musical instruments, the idea of using heartbeats as the rhythm controller shined in my mind. It would be so Interesting to perform with using what we cannot control but simply feel. Also, inspired by Principle 5.6: How to deisgn a new interface (A logical approximation) and Principle 5.16: Everyday objects suggest amusing controllers, I came up with an idea of using book as a musical instrument. When flipping pages, the sound of papers rubbing our fingertip is somewhat pleasing to me. If we use the frequency of page flips and the angle of the book opening as input parameters, our natual interations with a book could be mapped to musical expressions. I would be even better if the book itself is a music score. After reading the adventures in building the SLOrk, I strong believe in Principle I.2: Design == Co-design. I often question myself when I put a lot of efforts into aesthetics of my deisgn: visualizers, webpages, or even homework fonts, until I realized that design is the nature of our daily expressions. It is inherent in our ways of doing things, and we can never design only one aspect of things.