Xenophon, The Art of horsemanship, around 362 B.C

If you desire to handle a good war-horse so as to make his action the more magnificient and striking, you must refrain from pulling at his mouth with the bit as well as from spurring and whipping him. Most people think that this is the way to make him look fine ; but they only produce an effect exactly contrary to what they desire, - they positively blind their horses by jerking the mouth up instead of letting them look forward, and by spurring and striking scare them into disorder and danger.
This is the way horses behave that are fretted by their riders into ugly and ungraceful action ; but if you teach your horse to go with a light hand on the bit, and yet to hold his head well up and to arch his neck, you will be making him do just what the animal himself glories and delights in.
A proof that he really delights in it is that when a horse is turned loose and runs off to join other horses, and especially towards mares, then he holds his head up as high as he can, arches his neck in the most spirited style, lifts his legs with free action, and raises his tail.
So when he is induced by a man to assume all the airs and graces which he puts on of himself when he is showing off voluntarily, the result is a horse that like s to be ridden, that presents a magnificent sight, that looks alert, that is the observed of all observers.

                                         (Translated by Morris H. Morgan, p. 55-56, J.A Allen & Company Limited, 1962.)