Xenophon, On the Art of Horsemanship
E. C. Marchant, G. W. Bowersock, tr. Constitution of the Athenians., Ed.

In case the intention is to buy a horse already ridden, we will write out some notes that the buyer must thoroughly master if he is not to be cheated over his purchase.

First, then, he must not fail to ascertain the age. A horse that has shed all his milk teeth does not afford much ground for pleasing expectations, and is not so easily got rid of.¹ [2]

If he is clearly a youngster, one must notice further how he receives the bit in his mouth and the headstall about his ears. This may best be noticed if the buyer sees the bridle put on and taken off again. [3]

Next, attention must be paid to his behaviour when he receives the rider on his back. For many horses will not readily accept a thing if they know beforehand that, if they accept it, they will be forced to work. [4]

Another thing to be observed is whether when mounted he is willing to leave his companions, or whether in passing standing horses he does not bolt towards them. Some too, in consequence of bad training run away from the riding ground to the paths that lead home. [5]

A horse with jaws unequally sensitive is detected by the exercise called the “ring,”² but much more by changing the exercise.³ For many do not attempt to bolt unless they have a bad mouth, and the road along which they can bolt home gives them their chance.⁴ It is likewise necessary to know whether, when going at full speed he can be pulled up sharp, and whether he turns readily. [6] And it is well to make sure whether he is equally willing to obey when roused by a blow. For a disobedient servant and a disobedient army are of course useless; and a disobedient horse is not only useless, but often behaves just like a traitor. [7]

As we have assumed that the horse to be bought is designed for war, he must be tested in all the particulars in which he is tested by war. These include springing across ditches, leaping over walls, rushing up banks, jumping down from banks. One must also try him by riding up and down hill and on a slope. All these experiments prove whether his spirit is strong and his body sound. [8]

Nevertheless, it is not necessary to reject a horse that is not perfect in these trials. For many break down in these not from want of ability, but from lack of experience. With teaching, use and discipline they will perform all these exercises well, provided they are otherwise sound and not faulty. [9] But one should beware of horses that are naturally shy. For timid horses give one no chance of using them to harm the enemy, and often throw their rider and put him in a very awkward situation. [10]

It is necessary also to find out whether the horse has any vice towards horses or towards men, and whether he will not stand tickling: for all these things prove troublesome to the owner. [11]

As regards objection to being bridled or mounted, and the other reactions, there is a much better way still of detecting these, namely, by trying to do over again, after the horse has finished his work, just what one did before starting on the ride. All horses that are willing after their work to do another spell thereby give sufficient proofs of a patient temper. [12]

To sum up: the horse that is sound in his feet, gentle and fairly speedy, has the will and the strength to stand work, and, above all, is obedient, is the horse that will, as a matter of course, give least trouble and the greatest measure of safety to his rider in warfare. But those that want a lot of driving on account of their laziness, or a lot of coaxing and attention on account of their high spirit, make constant demands on the rider's hands and rob him of confidence in moments of danger.