For these reasons, also, the scientific equitation insists on the absolute necessity of giving to the horse a factitious equilibrium in place of that which comes by instinct; not only in order to prevent disobedience, but also to remedy faults of conformation by a due combination of the animal's forces at the center of gravity. The entire education of the horse is, indeed, toward this result.
When the center of gravity is established, the horse is in a condition of equilibrium. The weight of the man, combining with that of the animal, becomes, by its position, an essential element in maintaining the center of gravity, in direct ratio to the displacement of this new force, forward, backward, to right or left of the perpendicular. If the man's weight shifts forward, the excess compels the horse to advance a base of support in order to prevent the fall. In this case, the center of gravity does not alter; the change is of the momentum. It is the same with movement backward, or to right or left, always supposing that the horse keeps its state of equilibrium.
