[3] "Mollia crura reponit," Virg. "Georg." iii. 76; Hom. "Hymn. ad
Merc."

How these desirable results are, in our opinion, to be produced, we
will now endeavour to explain. In the first place, then, you ought to
have at least two bits. One of these should be smooth, with discs of a
good size; the other should have heavy and flat discs[4] studded with
sharp spikes, so that when the horse seizes it and dislikes the
roughness he will drop it; then when the smooth is given him instead,
he is delighted with its smoothness, and whatever he has learnt before
upon the rough, he will perform with greater relish on the smooth. He
may certainly, out of contempt for its very smoothness, perpetually
try to get a purchase on it, and that is why we attach large discs to
the smooth bit, the effect of which is to make him open his mouth, and
drop the mouthpiece. It is possible to make the rough bit of every
degree of roughness by keeping it slack or taut.

[4] See Morgan, op. cit. p. 144 foll.

But, whatever the type of bit may be, let it in any case be flexible.
If it be stiff, at whatever point the horse seizes it he must take it
up bodily against his jaws; just as it does not matter at what point a
man takes hold of a bar of iron,[5] he lifts it as a whole. The other
flexibly constructed type acts like a chain (only the single point at
which you hold it remains stiff, the rest hangs loose); and while
perpetually hunting for the portion which escapes him, he lets the
mouthpiece go from his bars.[6] For this reason the rings are hung in
the middle from the two axles,[7] so that while feeling for them with
his tongue and teeth he may neglect to take the bit up against his