She starts off by taking issue with the definition of 'dressage' as "the systematic training of the horse". She proposes instead to redefine it as "the process through which riders inter-act with their horses from moment to moment, and learn the skills to do so in more refined and effective ways." For me, this works as a definition of riding full stop. It is not restricted to those "doing" dressage. At the other end of the spectrum, even a rider who "just" hacks their horse out on the trails can interact with their horse from moment to moment, learning to do so in more refined and effective ways.
( Cut for - as usual - length! )
"On the way to this lie many blind alleys, and many cycles of 10,000 repetitions. For if you are a disorganisd rider, your horse will succeed in disorganising you more, and only when you are a highly organised rider will you be able to organise the disorganised horse. You will then earn his respect, and perhaps even his love. But do not expect that the game will then be over, for our horses cannot not play it. Whenever you absent yourself mentally, for instance, your horse will find the loophole that you have just created."
Which brings us back to the model of the Push Hands competitors - our horses cannot but sense and respond to the weaknesses in our bodies and our riding form, neither can they refrain from offering challenges to our physical integrity as riders - though the way they may do so differs from horse to horse. However, these challenges are not meant personally, they are merely part of the kinaesthetic language of Horse. The only answer is for us to improve the skill with which we can communicate to them in that language - a lifelong challenge!