In Chap­ter Six Hun­dred and Forty-Three of “Moth­er Night,” the pro­tag­o­nist reflects on a man­u­script titled *Mem­oirs of a Monog­a­mous Casano­va*, which details his inti­mate expe­ri­ences with his wife, Hel­ga. Despite con­sid­er­ing the man­u­script unpub­lish­able, he views it as a means of main­tain­ing their sex­u­al excite­ment and con­nec­tion. The man­u­script is described as clin­i­cal, focus­ing sole­ly on their erot­ic life dur­ing their two years apart dur­ing the war, devoid of any con­tex­tu­al set­tings.

The chap­ter includes a poignant excerpt, Chap­ter 643 of the man­u­script, recount­ing a night spent in a New York hotel with Hel­ga after a six­teen-year sep­a­ra­tion. The pro­tag­o­nist vivid­ly describes the rekin­dling of their inti­ma­cy, feel­ing youth­ful and full of won­der despite his age. He high­lights the plea­sur­able and ten­der touch­es, empha­siz­ing a con­nec­tion that tran­scends mere phys­i­cal­i­ty. Their pas­sion­ate reunion cul­mi­nates in a moment where they exchange sim­ple yet mean­ing­ful greet­ings, encap­su­lat­ing the deep bond formed over years of sep­a­ra­tion.

The scene shifts to the next morn­ing, where the cou­ple steps out into the bright city, indulging in a sense of reju­ve­na­tion after their night togeth­er. Dressed in a lav­ish fur-col­lared cloak and car­ry­ing a cane, he express­es delight in their mutu­al respect and affec­tion. They set out to pur­chase a bed sim­i­lar to their for­mer one in Berlin, but they dis­cov­er that all the stores are closed, caus­ing a moment of con­fu­sion.

As they walk, they notice Amer­i­can flags fly­ing and spec­u­late about the sig­nif­i­cance of the day, ini­tial­ly pon­der­ing a poten­tial dec­la­ra­tion of war. After encoun­ter­ing a uni­formed man, they learn it is Vet­er­ans’ Day, pre­vi­ous­ly known as Armistice Day. The pro­tag­o­nist express­es dis­con­tent over the loss of the day’s orig­i­nal mean­ing, reflect­ing on how soci­ety cou­ples nos­tal­gia with com­mer­cial­iza­tion.

Their con­ver­sa­tion turns intro­spec­tive as Hel­ga ques­tions whether the war has altered their love or feel­ings toward each oth­er. They engage in a heart­felt dia­logue about their love’s endurance, a con­nec­tion that shapes their under­stand­ing of each oth­er. How­ev­er, the chap­ter con­cludes with a shock­ing rev­e­la­tion from Hel­ga, who dis­clos­es she is actu­al­ly her sis­ter Resi, not Hel­ga her­self, leav­ing a cliffhang­er that chal­lenges the pro­tag­o­nist’s under­stand­ing of their rela­tion­ship.