The wedding eve arrives while Simoun packs arms and jewels, prepares gifts, and plans to leave with the departing Captain-General as gossip calls him devil, locust, or coward without military cover. He orders Basilio admitted if he comes, then broods until the student appears transformed: hollow, unkempt, eyes lit by prison and grief for Juli, speaking like a corpse back from eternity. Basilio confesses he wronged his mother and brother by silence, accepts God's chastisement, and now demands to return evil for evil, crime for crime, offering himself to the revolution he once refused when it failed three months ago.
Simoun's doubt vanishes; he praises Basilio as proof that even a gentle dove sees the need for force and leads him to the nitro-glycerin lamp shaped like a pomegranate, concentrated tears and repressed hatred meant for tyrants hidden behind God and State. He explains the wedding fiesta trap: brilliant light for twenty minutes, then fulminate of mercury when the wick is turned, powder in floor and roof, an explosion to rally Cabesang Tales, misled soldiers, and a panicked mob toward Quiroga's rifles while Basilio seizes bridges and slaughters anyone who will not join. Simoun's social Darwinism celebrates twenty thousand deaths as renewal; Basilio, weakened and vengeful, asks only what the world will say, then accepts that society owes him nothing.
Rizal's narrator lists the moral replies Basilio never makes: souls can be redeemed, no man may trade lives for another, wretched people must not pay for rulers' crimes, only God may destroy to create. Instead Basilio loads Simoun's revolver, agrees to meet at St Sebastian at ten, and leaves with a curt promise to return, while Simoun tells him to stay far from Calle Anloague at nine. The chapter title is the ultimate reason: when reform, pity, and Juli are gone, revenge dresses itself as natural law.
Rizal does not endorse the bomb; he shows how colonial cruelty manufactures disciples. Simoun needed Basilio's consent to feel righteous; Basilio needed a target for pain. When the last idealist picks up a weapon, who will be in the wedding hall besides the tyrants Simoun names?