explained by late Miguel Tavora:
(posted 3-24-22)
“In the first place we have to admit that it is not possible to school a horse without the shoulder in. La Guérinière stated that this one should be the first and last lesson to give to a horse, Nuno Oliviera said that it was the aspirin of the equitation. We start with the shoulder in from the beginning and once the horse knows how to execute it, we make the descent of hand on the side of the bending (inside) to make the horse take the habit of keeping the shoulder-in in self carriage and without the constant use of our aids being necessary.”