Carl's practice was deeply rooted in the intellectual and the metaphysical through both western and eastern philosophy. In the title of this work, he uses the term "Koan" which originates from Zen Buddhism. "Koans" typically refer to "illogical thought processes that can bring about an alternative state of mind allowing one to gain insights that might otherwise not be accessible" (pg 21 NGC catalogue). In this work, Carl has paired text and imagery, a human skeleton and bird wing, to question the underlying structure required for flight or lift, suggesting a "koan" that permits both a literal and a figurative interpretation. TF