Not very well written. It almost felt like the chapters were a transcribed lecture series. I found that there were too many references throughout the book to the same examples such that I often skipped paragraphs. Interesting concepts, yes, and several thought-provoking ideas that resolved such things (in my mind) as to why Humans are #1 on this planet: bi-pedal is a distinct advantage! I did enjoy the reference to Steven Jay Gould and "re-playing the tape" thought-experiments. Constructal law identifies where SJG's conjecture is seriously challenged (in my mind). I thoroughly enjoyed the underlying theme at how the contructal law brings physics into biology - which is now resolved for me, thank you Dr. Bejan! Yet, there are unanswered questions that may invoke a future book or research area: what about light? This topic was avoided, and my guess is that light cannot be eaily defined as flowing. Can't we have a chapter, or a few paragraphs to address it?