Ross Jakobs has an amazing way of thinking and writing about horses and riding. Always surprising, and always to the point (once you get your head round the question he addresses).
Here is a taster: the important distinction between obedience and willingness: Obedience = a horse doing something because it believes NOT DOING it leads to discomfort. Willingness = a horse doing something because it believes DOING it leads to comfort
You can read his thoughts on above question here: https://www.facebook.com/275719312528545/photos/a.275872839179859/2063117107122081/
Here is a taster: the important distinction between obedience and willingness: Obedience = a horse doing something because it believes NOT DOING it leads to discomfort. Willingness = a horse doing something because it believes DOING it leads to comfort
You can read his thoughts on above question here: https://www.facebook.com/275719312528545/photos/a.275872839179859/2063117107122081/