Horses are prey animals. The run in herds--like all prey animals-- for protection and safety.
Their eyes are far apart to allow maximum coverage of their surroundings at the sacrifice of not being to determine distance.
The leader of the herd--and yes there is a leader--determines everything. She does this by gaining control of all of the other horses feet. If she say run they all run without question. If she says stop they all stop. Turn left, turn right, back up and its done right now.
This concept is the backbone of their language and society. It is what comes natural for all except the lead mare.
From there there is a ranking within the herd. 1, 2, 3, 4 etc,. Three comes before 4 so four does what 3 says. There is no equal footing. Again this is part of their society an is natural or normal.
The lead mare does not take contol, the others give it. Is this process physical--absolutely. Horses speak wiht the physical not the verbal--its their language.
Once respect is given trust follows but the horse knows that there can be no trust without respect--and I mean mutual respect.
Even then--when trust is given--the number 2 or 3 or 4 or... tests the lead mare each and every day to be sure that she is still capable of being number one. Remember that their very life depends on whether or not she is up to the task. No offense meant, no offense taken.
All successful training methods use this as a basis for achieving the end result--gaining control of the horses feet.
Each and every horse is a individual and as individuals the methods are applied differently to achieve the end result--gaining control of their feet.
Understanding them and dealing with them in the way that they understand is the key to building a good relationship between them and the human.
Forcing them to become more human usually results in chaos.