That is an excellent question. This type of feel communicates with the nervous system. We want to influence the nervous system as it dictates and controls how the body holds at an unconscious level - this is important because the body will put tension in certain areas to protect itself which is good, but after a period of time it becomes "stuck" in that often unnecessary tension and holding pattern and the body loses conscious awareness of the extra tension is there - it become the new normal. So when we apply very gentle touch we can bring the nervous system's awareness to that area of the body in such a gentle way that it does not generate an automatic (and unconscious) reflexive response (e.g., to brace an area that is sore when someone pushes into it). When we see the horse processing, this is a strong indication that the brain is reconsidering and making changes to how it is holding that area of the body.