I think that Buna is significant because it is the setting where so much of Eliezer's view towards consciousness undergoes significant change. Buna is the point where Eliezer repudiates the notion of God and of his redemption. It is at Buna where he is exposed to the very worst of human nature, both in his own experiences and in the experiences of other people. It is at Buna where Eliezer begins to devolve, in a way, in terms of becoming a human being where survival is all that matters and where human attachment is seen as nothing more than a weight in a setting of dehumanization. Buna is significant because it is a point where the work moves into a philosophical realm that forces the reader to endure the emotional and spiritual challenges that Eliezer must confront. What defines human beings? Is there a God? How can there be redemption in the face of such overwhelming sorrow? It is at Buna where God is "there, in this gallows." In this, there is significant analysis and intense reflection that is forced upon the reader. I would say that this becomes Buna's most significant contribution to the narrative.