Bris mila teaches us that man must rise above nature. The seven days of the week symbolize the realm of natural forces, since the physical world was created in seven days. Bris mila is performed on the eighth day of a child’s life to symbolize the goal of rising above nature. Adam was born circumcised since he was a superior being, however he failed to maintain himself on this level. By sinning he fell prey to the natural forces which originally were there to serve him. Avrohom saw miracles everywhere in the physical world, and the various natural abstractions that existed withered away. With this realization he placed himself above the rule of the physical seven day world. Hashem saw this change in Avrohom and therefore gave him the mitzvah of Bris mila.
