Equus

One of the first things Alan notices about horses is the chains that bind them. He is fixated on the bits in their mouths and the reins around their necks, seeing these as despicable means of confinement and constriction. This is primarily because Alan himself feels confined by the life he lives and the expectations of his parents and of society, when truly all he wants is a sense of freedom. Alan achieves this freedom through his midnight field rides on Nugget's back, with both horse and rider completely naked and free of the ties that bind them -- a freedom which he conflates with the sexual act.