Overread, you have/have had dogs? (Going by your avatar). You probably know their little 'quirks'. When the lay down and give a hefty sigh because you didn't feed them, or they sit at the door and look from you to the door because they want to go for a walk or a hundred other little things, and things more subtle...? Well it is pretty much the same intuitions/senses/vibes with a horse. Just to begin with you may need to consciously look for it.
Aye, though its taken me 10 years I think we are still trying to understand husky talk. Sometimes its easy and you can most certainly connect the dots between certain types of behaviour and what the animal is trying to say or want or feel. However there are also other bits where you can't so easily connect the dots; where you sometimes need experience or input from a source that has looked at way more information and example of behaviour to put it all together.
And of course each animal is individual and how they are raised and what they are will affect a lot of their talk. A horse in the wild won't speak quite the same language as a horse kept stalled its whole life ; but there will always be common elements that link the two as they are still horses at the end of the day.
For me this is about trying to "cheat" on years of observation by getting some second hand information. Giving a structured framework to build upon when dealing with horses infrequently or when there isn't a horsey person around to say "Oh that means XYZ"
Interestingly on the subject of horse communication or indeed any animal I think there are two parts.
1) Understanding; actually understanding what the animal is saying.
2) Responding; responding to that or not responding and sometimes knowing how to respond.
For the newbie, like myself, both parts are a key problem. A horse might well send a very clear message; but its then (at least when interacting with) also knowing how to respond to that message.
My hope is that by at least aiming to learn as much as I can of the former the latter will be more easily learnt. Furthermore I think the former is critical to how one chooses the latter as there are often multiple ways to respond to the same message; so a greater understanding of the message opens up a greater capacity to pick the right response.
Which is exactly what you're talking about greentree in how its understanding the horses language and then responding in kind to that message; in your case also then adapting it all to mould your desires around - in your example your desire to ride mixed with the horses language to accept being ridden.
The discussion on some of the big names in the horsemanship world are interesting and its interesting to hear not just about but first person stories regarding some of them and how they react around horses. What's interesting is that I see some making mistakes that I would consider more akin to beginner level mistakes - especially ones where you can see the trainer has gone into a situation or been presented with a situation where there's a demand for a certain end result and everything they do gets "blinkered" to that end goal regardless of what the animal is communicating. The story about the trainer ignoring the horses lameness in favour of focusing on the objective of riding/jumping being a prime example of this.
It woudln't surprise me if that trainer could see the message in the movements of the horse but was focused purely on their target of jumping the horse