I have had the good fortune to be loaned a highly entertaining and interesting book.  It was written by Henry Earl of Pembroke, and first published around 1761 in order to lay out "A method of breaking horses, and teaching soldiers to ride" within the army.

Much of what Pembroke writes is remarkably enlightened and insightful, particularly given that it was written several hundred years ago.  I will reproduce an example of this writing below:

CHAP. VIII

The method of curing restivenesses, vices, defences, starting and stumbling, etc.

Before any mention is made of the different kinds of restivenesses, vices, and defences, etc. it is not amiss to observe, that a horse's being good or ill-natured greatly depends on the temper of the person, that is put about him, especially at first; and consequently one cannot be too careful and watchful in this point.

Whenever a horse makes resistance, one ought, before a remedy or correction is thought of, to examine very minutely all the tackle about him, if any thing hurts or tickles him, whether he has any natural or accidental weakness, or in short any the least impediment in any part.  For want of this precaution, and previous inspection, many fatal, and often irreparable disasters happen: the poor dumb animal is frequently accused falsely of being restive and vicious; is used ill without reason, and being forced into despair, is, in a manner, obliged to act accordingly, be his temper and inclination ever so well disposed.  It must never be forgot, that it is necessary to work on the minds of horses, at first by slow motions which give them time to reflect.  By degrees every thing may be done most rapidly by us, the good temper, docility, and obedience of a horse, that almost any thing may be done with him by good-nature, and science.  Even the domestic, worthy, friendly dog is not more susceptible of education.

Pembroke does tackle the subject of punishment also - whilst he sees harsh punishment as generally unnecessary if a horse is well trained from the outset, he does go out of his way to describe how to use it ... effectively ... (you'll see what I mean) in certain circumstances.

Rearing is a bad vice, and in weak horses especially, a very dangerous one.  Whilst the horse is up, the rider must yield his hand, and when the horse is descending he must vigorously determine him forwards by approaching his legs to the horse's sides: if this be done at any other time, but whilst the horse is coming down, it may add a spring to his rearing and make him fall backwards.  With a good hand on them, horses seldom persist in this vice; for they are themselves naturally much afraid of falling backwards.  If this method, which I have mentioned, fails, (which it scarcely ever will) you must make the horse kick up behind, by getting somebody on foot to strike him behind with a whip; or, if that will not effect it, by pricking him with a goad.

Pembroke seems like the type of man who calls a spade a spade.  To his credit, his general attitude towards punishment is described in the following:

When a rider quarrels with his horse, he is generally the dupe of his passion, and the fray commonly ends to his disadvantage.  Whenever you see a man beating any animal, you will almost always find, that the man is in the wrong, and the animal in the right.

What a fantastic insight into the culture that surrounded horse training in the 18th century.