A horse is in “collection” when he is gathered and his hind legs are well up under the body.
When a horse is collected, the rider, by having omitted bending the neck near the shoulders during training, has the neck firm on the shoulders and not flexible or “rubber-necked.” Hence the rider acts on the neck through the mouth and on the shoulders through the neck. The hind quarters by being under the horse bind themselves to the forehand. The rider then by acting on the forehand acts likewise upon the hind quarters.
The entire body of the horse should be, if properly collected, an energetic and harmonious whole. The horse is “in hand,” because his jaw is flexible and he yields to the effects of the bit. The horse is light or handy, because he is balanced by continual training and because his center of gravity is equally near both front and hind quarters; hence the proper movement on the part of the rider will disturb this balance in any direction desired.
The rider at this point, being supposed to be able to get the hind legs up under the horse, must learn to gather him.
To gather the horse involves:
1. Direct flexion (the flexion of the jaw and head in the direction of the axis of the horse.)
2. Lateral flexion (the flexion of the neck at the poll in a direction perpendicular to the axis of the horse).
Direct Flexion.—Direct flexion is the concession the head and lower jaw of the horse make in the vertical plane of the axis, of the horse when the action of the reins arrests the extension of the neck. The giving of the neck is confined to the upper portions; the front line of the face is made to approach a vertical line and the head is made to make in an almost imperceptible manner a movement analogous to a nod.
The giving of the jaw consists in opening the mouth, causing complete abandon of the bit, followed immediately by the closing of the mouth and the taking up of contact with the bit again.