The anti-hypochondriac plaster is the invention to which Brás Cubas attributes his own death: a remedy "meant to ease our melancholy humanity". He presents it to the government as a Christian work, but confesses, after death, that the main motive was another: "the pleasure of seeing printed in the newspapers, shop counters, pamphlets, street corners" the three words "Emplasto Brás Cubas".
The plaster never comes to exist as a remedy. Brás says that, busy with it, he caught a blast of air, treated himself without method and died of pneumonia, and he admits the proof is weak: "There are less lucid demonstrations, and none less triumphant". The desire for the name comes from the father, who, thinking that the surname smelled of cooperage, invented that the tubs came from three hundred taken from the Moors; the son wants the surname on the little boxes of the remedy.
After the fifth chapter, nothing in the book shows Brás working on the plaster, but what it represented passes to other forms: the renown his father teaches him to want, the pleasure of seeing himself a minister, the desire to stir things up. In the last chapter, the plaster is among the ambitions that were not fulfilled, alongside the ministerial portfolio and marriage; Brás calls it "divine plaster" and says the affair determined the opposite of what he promised.
Two readings are possible. The plaster is the vanity of an idler with a varnish of philanthropy, or it is the melancholy that Brás himself knows, treated by the only route he knows, that of making himself noticed. In either case, the remedy that was to cure everyone's sadness ends up being the name of a man.