When the horse has to be led, we do not approve of leading him from in
front, for the simple reason that the person so leading him robs
himself of his power of self-protection, whilst he leaves the horse
freedom to do what he likes. On the other hand, we take a like
exception to the plan of training the horse to go forward on a long
rein[1] and lead the way, and for this reason: it gives the horse the
opportunity of mischief, in whichever direction he likes, on either
flank, and the power also to turn right about and face his driver. How
can a troop of horses be kept free of one another, if driven in this
fashion from behind?--whereas a horse accustomed to be led from the
side will have least power of mischief to horse or man, and at the
same time be in the best position to be mounted by the rider at a
moment's notice, were it necessary.

[1] See a passage from Strattis, "Chrys." 2 (Pollux, x. 55), {prosage
ton polon atrema, proslabon ton agogea brakhuteron. oukh oras oti
abolos estin}.

In order to insert the bit correctly the groom should, in the first
place, approach on the near[2] side of the horse, and then throwing
the reins over his head, let them drop loosely on the withers; raise
the headstall in his right hand, and with his left present the bit. If
the horse will take the bit, it is a simple business to adjust the
strap of the headstall; but if he refuses to open his mouth, the groom
must hold the bit against the teeth and at the same time insert the
thumb[3] of his left hand inside the horse's jaws. Most horses will
open their mouths to that operation. But if he still refuses, then the
groom must press the lip against the tush[4]; very few horses will
refuse the bit, when that is done to them.[5]