This is true, but i also think trainers sometimes put us on horses that are more than we can handle so we can understand. My instructor had watched me ride my bombproof horse in about 4 lessons and then put me on one of her arabians. The horse was not, contrary to popular belief, crazy, but he moved faster and was more sensitive than anything i had ever ridden before. I was scared, and realized how much my bombproof horse still had to teach me. I now ride lots of different types of horses comfortably, and also have my own arabian! :) A little eye-opener can sometimes help us understand what level we really are on, knock or ego down a few notches, and keep us safer in the long run!