In his Drama for Students, Christopher G. Busiel describes the theme of Equus as "man’s attempt to reconcile the personal and the metaphysical aspects of his universe." And herein lie the ironies of Shaffer's drama. In this attempt at reconciliation of aspects, madness becomes the subject. The primary subject of this madness is the patient of Dr. Dysart, Alan Strang, who most attracts the viewers' attention as he has committed an unspeakable cruelty to animals: he who has worshiped the horse as god--Equus--has blinded six horses with a spike.
Shaffer's naming of the drama's personages exemplifies verbal irony as these suggest characteristics that prove to be the opposite of what the person is like. The most salient of these is the name of the father, Frank Strang. For, the adjective frank denotes the quality of being honest, open, and direct. Of course, his conduct at the cinema where the "skinflick" is shown is completely dishonest as he tells his son that the owner had contacted him to make a poster for him.
Likewise, Alan Strang is not as odd as his surname suggests. He has an imagination that the psychiatrist ends up envying, and his psychoses have developed because of his religiously fanatic mother who teaches him that eroticism is sinful and God is essentially punitive, and his father denies him the enjoyment of television.
After the audience learns that Frank has become obsessed with the picture of the horse which his father has replaced the religious picture provided by his mother and Frank begins to worship Equus, they become aware that it is the father's picture which has more influence upon him than that of the mother's. However, Frank Strang does not realize that he has caused the boy's sadomasochistic switch from Jesus to horses; instead, he places blame upon his wife in a visit to Dr. Dysart, telling him of his observance of Alan reciting in mockery of the Bible by saying "Flankus begat Spankus...." and flagellating himself after saying, "Behold--I give you Equus, my only begotten son." Ending his tale, Mr. Strang says, "Religion's at the bottom of all this!"
The main incident that occurs which contradicts the expectations of Hesther Salomon and, certainly, the audience comes with the words of Dr. Dysart who, after analyzing Alan and providing him psychiatric therapy, and removing “parts of individuality repugnant to this God," tells Hesther that he envies Alan:
"That boy has known a passion more ferocious than I have felt in any second of my life. I envy it....
I can't get that far. I will, however, pay it [Alan's passion] so much homage. There is now, in my mouth, this sharp chain. And it never comes out."
His having provided therapy to Alan has helped him, but ironically his passion has been diminished,
"[that kind of ] passion you see can be destroyed by a doctor. It cannot be created."
Another example of situational irony occurs after Alan discovers that his father frequents the "skinflicks." He tells Jill,
"I just thought about Dad was nothing special--just a poor old sod on his own."