In the final chapter of the novel, Aschenbach's obsession with Tadzio begins to take a real toll on his mental and physical health. Increasingly ashamed of his age, which he feels contrasts unflatteringly with the youth and beauty of Tadzio, he seeks out a hotel barber who uses a combination of logos and fallacy in his argument that Aschenbach should dye his graying hair a darker color:
“Gray,” he said, with distorted mouth. “A bit,” the fellow replied. “And all because of a little negligence, an indifference to external things, which is understandable in important people, but is nevertheless not altogether praiseworthy, especially since it is just those people who should be free of prejudices about what is natural and what is artificial. If certain individuals’ moral objection to the cosmetic art were to be logically extended to the care of their teeth, they would give quite a bit of offense. After all, we are only as old as our mind and heart feel [...]
The barber argues that Aschenbach's gray hair is the result of "negligence," as the middle-aged man (like other "important people") desires to affect "an indifference to external things" and has therefore neglected to dye his hair. Employing logos, he states that this feigned indifference is not necessarily "praiseworthy," since a novelist who works with fiction and the imagination should be "free of prejudices about what is natural and artificial." Further, he reasons, many of those who consider "the cosmetic art" to be vain nevertheless take care to keep their teeth white. The barber, who is attempting to sell his services to Aschenbach, is occasionally faulty in his reasoning, employing both logos and fallacy. Poor dental care, for example, can severely impact an individual's health, and is therefore meaningfully distinct from Aschenbach's vain desire to appear younger through makeup.
Nevertheless, Aschenbach is, by this point in the novel, crazed by his fixation with Tadzio and accepts the barber's offer to dye his hair and employ makeup in order to appear closer in age to Tadzio. In a moment of situational irony, then, Aschenbach now appears much like the elder man on the boat who was an object of revulsion to Aschenbach for his apparent vanity in wearing a wig and dressing in youthful fashions.