Very good IMO. The Dolphin thing was about Dolphins selecting the frequencies that they use and so do humans. How Dolphins select their frequencies might depend on their DNA makeup and evolution etc but they do select certain frequencies as does a Bat or whatever. Humans are no different in selecting frequencies that appeal to their genetic makeup and when we start playing around with them they can end up with something we call music. The mathematical ratios of this or that probably do come into it because the mathematical patterns do exist in the natural world and all species have their genetics adapting to things in the natural world over time and human hearing is one of them. What I don't really agree with is that it can all be explained simply with a few ratios and a bit of pythagoras or whatever by some people who write their own books where they can proceed with their own views and have no "hold on for a moment let's go over that" feedback. There are mathematics in musical theory and the the so called JI and ET are just different ways of dealing with frequencies bound by octave repeating (octave repeating is part of nature btw). I've already given an example of a Saxophones overtones and what they are and what they do as the lowest note of the overtone series is disturbed (or removed) one by one up the overtone series. They realign into their own overtone series starting on each rung of the overtones series. Without these overtones, a Saxophone would be limited to one octave. No one has control of a Saxophones overtone series as it's a consequence of cones and if someone makes a noise using a cone then they will get the cone overtone series and if they do it with a cylinder then they will get the Clarinet's overtone series which are different to a Saxophone's cone overtone series. Someone is stuck with cone or cylinder overtones if they play some wind instruments. All of John Coltrane's output was with a ET Saxophone with the toneholes positioned for ET. He was attracted to World Music later on (non ET) and tried to include some of it in his playing but he was using ET while doing so. He could of course hit pitches between the ET pitches and he did, and so have Blues players for decades. Just using JI is not by itself going to lead to wonderfully pure music that is magical. ET is a practical system and it works but it's not perfect and neither is JI.