Book IV opens three weeks after the birthday celebration. Adam is superintending some repairs at the Chase Farm this day, and toward evening he has to pass through the grove in which Hetty and Arthur have been meeting. As he walks along, he suddenly sees the pair a short distance before him; they are kissing. When they notice his presence, Hetty hurries away, and Arthur strolls casually towards Adam. He tries to pass the incident off with a few casual words, but Adam is furious; now he knows where the locket came from. He berates Arthur for trifling with Hetty's feelings and for stealing her affection from him. Arthur tries to make excuses, saying he meant no harm. He is about to leave to join his regiment (he is a captain in the local militia), and points out that the affair is about to come to an end. But Adam is not so easily placated; "you've robbed me o' my happiness," he exclaims and challenges Arthur to fight. Arthur is unwilling, but Adam calls him a coward and the fight starts. It is soon over, and Arthur lies on the ground unconscious.
After a few moments, Arthur revives. Adam is no longer angry. He brings water, then helps Arthur to the Hermitage, a cottage in the woods which has been Hetty and Arthur's trysting place, and Arthur slowly revives. Adam leaves to get brandy, and while he is gone Arthur hides a woman's kerchief. When Adam returns, he apologizes for judging Arthur rashly but asks for an explanation of his relationship with Hetty. Arthur lies again, saying that it has been nothing but a mild flirtation. He betrays guilt, though, and Adam is suspicious that Hetty's heart has been captured permanently. He demands that Arthur write Hetty a note breaking off the affair if he really cares nothing for her. Arthur unwillingly agrees and promises to put the note in Adam's hands the following day.
These are, both mathematically and structurally, the central chapters in the novel. In Books I, II, and III, Eliot has created a complex situation with the triangle; here the conflict implied in that situation explodes, and in Books IV, V, and VI, Eliot will trace out the consequences to which the situation gives rise. The happy world in which the characters existed is now shattered, and the fortunes of all three (for a limited time in Adam's case) go downhill from this point. The relationships among the members of the triangle shift radically as the characters begin to see through appearances to the reality hidden beneath. Adam and Arthur no longer see one another as friends, Adam no longer sees Hetty as totally innocent (though he places the blame for this on Arthur and excuses Hetty), and Arthur can no longer see himself as good. Finally, the central character's journey towards spiritual maturity begins here; from this chapter on he moves away from pride towards humility and, in a parallel movement, loses Hetty and gains Dinah.
The fight itself is significant not only because it brings the previously unrealized conflict into the open but also because it forms the most striking illustration of the operation of Adam's pride. It is a touchstone incident representing that sort of reaction which Adam must learn to avoid; Eliot refers to it again later on when Adam has turned in the direction of a more mature outlook on life.
Adam's primary traits, in their negative aspects, emerge in the confrontation with Arthur. As we have seen, Adam is aggressive, straightforward, and practical in dealing with difficulties, and his behavior here is completely in character. All sympathy for any viewpoint other than his own disappears, as does his normally mild manner. He is suddenly "hard," "harsh," "blind with passion"; we are told at one point that "if he had moved a muscle, he must inevitably have sprung upon Arthur like a tiger." He typically seeks the simplest solution to the problem; he subdues Arthur and then demands that he clarify the situation in the most direct way by writing to Hetty immediately. Adam will listen to no excuses and requires rather tyranically that everything be handled his way. He is, as usual, concentrating on controlling events by taking practical steps and by exercising force of will.
Arthur's behavior is just as typical. Adam says, "It'll be better for me to speak plain," and he does; Arthur lies and squirms in order to avoid facing the consequences of his actions. He had repeatedly weakened in his resolution to end the affair, and now he cannot muster the courage to tell the truth. Arthur's way of dealing with unpleasant situations is to run away from them; he cannot make a decision which involves self-sacrifice unless he is forced to it.
Adam does quite literally force him to it, and this involves an interesting reversal. We noted earlier that Eliot draws her upper- and lower-class characters in such a way as to suggest that the latter are superior to the former. Here she makes the same point rather bluntly. When Arthur tries to bluff Adam on the question of the note to Hetty, Adam says that he respects Arthur's high position but that in this situation "we're man and man and I can't give up." On a man-to-man basis, Adam is clearly superior to Arthur and can bend him to his will. Social and natural standards of superiority are clearly out of place.
The reader should notice also that the fight, like the seduction, takes place in natural surroundings. This reflects one of the few symbol patterns which Eliot uses in Adam Bede. In keeping with one of her major themes — that one must act cautiously and prudently in order to avoid "terrible consequences" — the author sets up a contrast between nature and civilization, or, by extension, between actions which flow from natural urges and those which are logically thought out and controlled. The sin which triggers the novel's conflict is a "natural" one; Adam's fight with Arthur, which he later regrets, is a spontaneous reaction. By placing both actions in a grove, Eliot labels them as natural; by showing what great harm they cause, she points out that man must not act from instinct alone. He must exercise his intellect and will; "nature" is not a safe guide.