The Inferno, Henri Barbusse's 1908 novel, is a brilliant examination of the philosophy of solipsism, which is the idea that knowledge outside of one's own mind is essentially unobtainable. Solipsism conjectures that the external world and the minds of other people can never be known to truly exist. The narrative follows an unnamed man who by cutting a hole in his room gains a view to the outside world. He voyeuristically bears witness to the full breadth of human experience and emotion. He witnesses love, death, adultery, and birth and considers the philosophical implications of all that he sees. Considered by some as a shocking work of voyeurism when it first appeared, "The Inferno" is in fact a profound examination of the philosophy of solipsism.