Analysis: What's Up With the Ending?
The story's final, admittedly rather cryptic line, "You take a really sleepy man, Esmé, and he always stands a chance of again becoming a man with all his fac – with all his f-a-c-u-l-t-i-e-s intact" (163) refers to an earlier point in our tale. About midway through the story, as Esmé and the narrator (later known as Sergeant X) part ways at the tearoom, she gravely tells him that she hopes he makes it through the war "with all [his] faculties intact" (103).
Months later, after the war has ended, it turns out that Sergeant X didn't in fact leave the front unscathed; when we meet him again, he's on the brink of a nervous breakdown. However, one thing does bring him back from his depression – Esmé's letter. Her serious, earnest, and unintentionally comical missive gives him a sense of relief, and he finally feels some release of the tension he's been carrying around. For the first time in a long time, Sergeant X is able to let himself go a little, and finally feel healthily, productively sleepy. The story's closing line is a final "Thank you" to Esmé herself for bringing the narrator back from the war in one piece (mentally, that is).