The scene begins in the middle of a discussion between Hesther and Dysart. Dysart is lamenting the fact that he and his wife do not understand each other; Hesther admits that she never got the feeling they were compatible. Dysart says they used to be, and that she would keep him on his toes with certain briskness that was unique to her. He acknowledges that their entire relationship moved briskly, even briskly into disappointment.
He describes how they used to live in the same house yet be in two different worlds, him deeply immersed in his studies of Ancient Greek literature and art, a particular passion of his which she wanted nothing to do with. He expresses his desire to have someone to take to Greece who would understand how life is only comprehensible when you explain the world through a thousand gods, gods within everything from trees to buildings to people themselves.
Hesther makes to leave, but before she does, Dysart worries aloud that Alan is trying to save himself through his time with Dysart, and that what Dysart is trying to do in return is not helping him. Hesther says he is trying to restore him to a normal life; Dysart questions what "normal" is.
Another session with Alan begins; Dysart apologizes for the fight they had the previous day. To make Alan feel more relaxed, Dysart begins a game called blink, asking Alan to fix his gaze on a stain on the wall and blink when he taps his pen. As this continues, Dysart breaks into an aside about what "normal" really is, how a normal smile in a child's eyes could also be a dead stare in an adult, how the idea of normal brings about both good and bad, and how he, as a psychiatrist determined to correct erratic behaviors, is the normal's "priest." He acknowledges that by emphasizing what is "normal" in children, he has cut from them many aspects of their individuality.
We return to the situation at hand and Dysart has begun to hypnotize Alan. He begins to ask Alan questions under his hypnosis, notably about the day on the beach with the horseman. According to Alan, he asked the horse a question: "Does the chain hurt?", referring to the bit in his mouth. Within Alan's mind, the horse responds that it does, but that it can never be taken out—he is in chains forever. Dysart compares this to Jesus, to which Alan assents; however, Alan says the name of this horse is not Jesus – it is Equus. He says that Equus lives in all horses.
Dysart then questions the chanting in front of the photograph in the bedroom, and Alan says that Equus is in chains for the sins of the world. He says that Equus promised to bear him away, and they would become one being, horse and rider. When Alan admits to taking the horses out of Dalton's stables at night to ride them, Dysart guides him through the process while still under hypnosis, hoping to uncover the truth about what really happened.
In this vision, Alan goes into the stables and chooses Nugget to ride. He leads him out into the open air, and though Alan says Nugget does not like to go into the big field near the stable, Dysart makes Alan lead him into it anyway.
Alan describes being in this field to Dysart. He takes off all his clothes and bears himself completely to the horse, his God. He takes a stick into his mouth, calling it a "manbit," as a horse wears a bit. He gives Nugget a lump of sugar, calling it his Last Supper. Alan finally mounts Nugget (calling him Equus) and begins to chant the words he chanted in his bedroom in front of the horse photograph, clearly worshipping Equus. He claims that they ride against their foes—all of those who show off horses for their own vanity. He begins to scream and shout as they ride off, sexual tension mounting as he begs Equus to make horse and rider one person. The act ends with a powerful sexual climax in praise of Equus as Alan shouts "AMEN!"
It can be difficult to discern exactly what Dysart means when he speaks about the "briskness" of his wife and their relationship. But putting this in the context of Dysart's other complaints throughout the rest of the text makes it clear that he welcomed his wife Margaret's briskness at the beginning of their relationship, as she sped up and keyed up the life that he otherwise finds dull and unrewarding.
It turns out, though, that these clear differences between them were too much to allow them to maintain a happy relationship. Based on his conversation with Hesther, Dysart just wants to be with someone who can understand him—in this way he is not all that different from his clients, who are desperate to be understood.
This is not the first time Dysart's deep interest in Ancient Greece has come up, but in his Scene 18 conversation with Hesther, the reasoning behind this passion becomes clearer. Dysart is intrigued and humbled by the ancient Greeks' idea of gods being found within everything, in everything ranging from natural beings to objects of manmade design. As he quotes to Hesther, "Worship as many as you can see—and more will appear!" This desire to find a sense of spirituality in everything connects Dysart to Alan in a way that nothing else can, since Alan has found his own spirituality in the souls and spirits of horses.
The end of Act I digs deeply into one of the primary themes of this play: the concept of ‘normal’. Equus seeks to challenge the typical idea of normal, causing discomfort among audience members and readers as they attempt to define 'normal' themselves. Though Dysart has always grappled with these questions, treating Alan has made him even less certain that 'normal' is good. In Dysart's own life, 'normal' has left him dissatisfied, craving something beyond the dull existence he leads.
Further, Dysart questions whether he, as a psychiatrist, is doing the right thing by trying to make children normal. He calls himself normal's priest, and this religious metaphor fits well with both the religious themes of this play as well as his own earlier dream about sacrificing children as a Homeric priest. He believes that through his treatment, he may be robbing them of their individuality. This brings up some of this play's most important questions: who defines normal? And is normal truly desirable?
Hypnosis is the only way that Dysart is able to remove Alan's inhibitions and get him to reveal what he truly feels about these horses. It is blatantly obvious, now, that horses have become Alan's religion; he worships the god Equus, which he claims is a spirit that lives within all horses. Equus speaks to him, and Alan attempts to atone for humanity's sins against these equine gods. Equus promises Alan salvation by making he, the horse, and Alan, the rider, into one entity: "Horse and rider shall be one beast." This is in reference to many cultures' belief that horse and rider share a special connection. Earlier on in the play, Dora also referenced the pagans who believed that when the Christian cavalry arrived in the New World, the horse and its rider was all one person, and likely a god.
To Alan, one of the most important things that horses symbolize is freedom. He condemns those who chain horses, and even uses a "manbit" to chain himself instead; in his eyes, man is wrong for reigning in the freedom of these godlike creatures, and man is the one who should bear the punishment for this sin. Alan's moments of truest freedom come when he sneaks Nugget out of the stables to ride. He removes all of his clothes, because, to him, clothes are comparable to the chains that horses wear. They keep him confined and restrict both his freedom and his connection to his god, Equus. Alan needs this freedom after living a life controlled by his parents, who criticize his behavior because it is not 'normal'. The removal of clothes also functions as an indicator of the sexual nature of the scene, which culminates in Alan climaxing on the back of Nugget.