"the further one goes, the deeper one sinks. It's because the earth keeps turning around, around, around, around"
The Old Man provides an answer for why it gets darker earlier in Part One. He and the Old Woman lead lives of repetition, of routines that never advance but cycle continuously around themselves, and his image of the earth's revolutions captures this revolving stasis. He also alludes to the death such repetition comes before. Their lives are devoid of novelty and, while their routines, such as storytelling and fantasy conversations, aim to stave off boredom and make life bearable. However, the repetitions actually grind them into a routine that approaches death, "the deeper one sinks," as into the ground, just as the earth's revolutions, in the Old Man's mind, increase the darkness.
"At the end, at the end of the end of the city of Paris, there was, there was, was what?"
The Old Man asks the Old Woman this while trying to resume his story in Part Two. His repetitive phrasing itself leads to no finite end but continues delaying the destination at the "end of the end of the city of Paris." The three "of" prepositions that keep prolonging the sentence's conclusion, in addition to his stuttering "At the end" and "there was." While the Old Man's wife has a worse short-term memory, as she doses herself with salt each night so she will not remember his story, the Old Man's long-term memory blank means he has a similar problem accessing the past. This inaccessibility to the past means that his present life will be even more repetitive than its schedule suggests, since his mind can cycle around only events in the present. The Old Man's memory is not linear, stretching from his youth to his current age, but cyclical, blurring beginnings and endings. Hence, he does not know what lay at the end of Paris, just as he is unsure sometimes whether he is an old man, at the end of his own life, or an infantile orphan.
"'It's you who are responsible.'"
The Old Woman recounts that these are the couple's son's final words to them as he left, which occurs in Part Three. The son's story beforehand—about his parents' killing birds—makes little sense, so his labeling them responsible seems, at first reading, to be a throwaway line. But it can also be read as an ironic comment, in that the parents are not, in fact, responsible. The Old Man and Old Woman create fantasy lives to escape their real ones, they regret the past but do not take accountability for it, and the Old Man is not able to deliver his own message but relies on the Orator. The existentialist philosophers believed that only by taking responsibility for one's life could man's absurd condition acquire meaning. Everything we see of them suggests that the couple is not, in fact, responsible, and their meaningless life, one of illusion and grinding routine, is their own fault—just as their son's departure is most likely their fault, despite whatever we make of the bird story.
"I'm an orphandworfan."
The Old Man wails these words to the Old Woman in a fit, which occurs in Part Two. His belief that he is an orphan—coupled with his infantile manner of expression—is evidence of his confusion over beginnings and endings. In his cyclical, repetitive world where the past is mostly inaccessible, beginnings and endings are conflated. Likewise, he is ninety-five years old, but he still believes he is a child. His regression and immaturity also speaks to his irresponsibility as he sloughs off adult commitments and becomes a crying infant. His nonsense word—"dworfan"—presages the Orator's nonsense words when delivering the Old Man's message. According to the existentialists, since the Old Man has taken no responsibility, his message will remain absurd and irrational, just as the word "dworfan" is similarly meaningless.
This is one of the nonsense words the deaf and dumb Orator writes on the blackboard while delivering the Old Man's message, which occurs in Part Five. The message has no meaning because the Old Man's life has been irresponsible and, as the existentialists believed, only a life of responsibility can bear meaning. The Old Man's final touch of irresponsibility is putting the onus of conveying the message onto the Orator, since he feels he cannot express himself well. One can view the Orator's butchering the message along these lines of irresponsibility, in which case Ionesco is criticizing his own irresponsibility in not transmitting the message himself. However, another possibility is that Ionesco criticizes the Orator for not understanding his message. The Orator is essentially an actor, as he looks the part, is self- absorbed, and signs autographs. At any rate, he is a frustrated playwright who feels either he or his actors have failed his work.