Clearly one of the central ideas of this powerful and rather depressing text is that of existentialism and absurdism, which points towards the meaninglessness of life and all that we hold most dear and consider to be intrinsic parts of who we are as humans. This text charts the slow but sure decay of the humanity of the townspeople as the reality of their lives and their crisis situation hits home. Consider the following quote that explores this sense of meaninglessness and also questions their humanity:
Whereas in the early days of the plague they had been struck by the host of small details that, while meaning absolutely nothing to others, meant so much to them personally, and thus had realized, perhaps for the first time, the uniqueness of a man’s life; now, on the other hand, they took an interest only in what interested everyone else, they had only general ideas, and even their tenderest affections now seemed abstract, items of the common stock.
As a result of losing their individuality, the "small details" of their own lives, people have come to lose their humanity, and even their "tenderest affections" such as the bonds of love that unite us as humans appear to be "abstract, items of the common stock." Camus presents us with a picture of all that is most important to us as humans being shown to be ultimately worthless and unimportant in the light of what is happening to the townspeople. He makes an important statement about the value of what it means to be human, and the value of life itself. This is one of the key ideas that is presented to us in this text.