(Disclaimer: For a blog that supposedly represents the “beis”, this blog contains very frequent references to sex. It is tempting to ascribe this to the fact that I'm a single male, and thus think about these things all the time (Kiddushin 29b). But I prefer to ascribe this to the fact that sex, in the right circumstances, is an unavoidably important part of life. Most of the stories in Tanach are about sex or death, because those situations bring out the strongest emotions and present us with the hardest moral choices. It is natural, then, that many of the divrei Torah worth writing about should involve sex as well. The topic must of course be addressed with sufficient decency and reserve, but I try to do that, and hopefully I succeed.)
“I am El Shaddai: walk before me and be wholesome. I shall place my covenant between me and you, and I will make you very very numerous. As for me, behold my covenant is with you, and you shall be the father of many nations. Your name shall no longer be called Avram; your name shall be Avraham, for I have made you the father of many nations. I shall make you very very fruitful, and make you into peoples, and kings will descend from you. I shall uphold my covenant between me and you and your offspring forever after you, as an eternal covenant – to be God to you and your offspring after you. I shall give you and your offspring after you the land of your dwelling, all the land of Canaan, as an eternal inheritance, and I shall be their God.” (Breishit 17:1-8)
In these verses, the introduction to the covenant of “brit milah” which God makes with Avraham, the main focus is on offspring – how many there will be and how many nations they will become. To make this more concrete, the birth of Yitzchak (the first such offspring) is foretold. Later on, it is stated that the punishment for breaking the covenant (by not being circumcised) is “karet” - being “cut off” from your people. According to one prominent explanation, this means the end of one's family tree due to lack of descendants. If so, this is a fitting punishment, the exact reversal of the reward of having many descendants.
Why is circumcision the sign of this covenant? The obvious answer is that circumcision involves the sexual organ, and thus represents the covenant's focus on reproduction. But this answer is insufficient. Surely there are other, less violent, ways of symbolizing reproduction. Why must the symbolism be achieved by cutting off part of the body, even a useless part?
Perhaps the following comparison will help illustrate why. Circumcision consists of the removal of a piece of skin or a membrane from the surface of the male genitals. Women, too, possess a membrane on the surface of their genitals. It too is removed at some point in their lives, stereotypically, when they begin married life. The removal is a necessary condition for them to become pregnant and have children. Perhaps male circumcision is meant to parallel this change in the woman's body. Just as the woman's genitals must be exposed before a couple can have offspring, so too the man's genitals be exposed.
Of course, there is a difference between the modifications. Rupture of the hymen is a natural process, and is a physical prerequisite for pregnancy and birth. Circumcision, in contrast, does not benefit for the reproductive process (on the contrary, it somewhat resembles castration, which prevents reproduction). But for a believing Jew circumcision is equally a prerequisite to birth, since in return for it God rewards us with offspring. The foreskin is a spiritual “impediment” to birth, just like the physical impediment in the woman's body. Removing both “impediments” demonstrates our faith in God's control of the world: that it is run by reward and punishment, not only by deterministic natural processes.
Midrash Tanhuma (Tazria) tells the story of a Roman who asked Rabbi Akiva whether circumcision did not contradict the idea that things made by God are perfect, and thus in no need of human improvement. R' Akiva replied with the example of bread: a loaf of bread is surely superior to wheat kernels, but God only made the kernels, and left us to finish the job by grinding flour and baking bread. Similarly, God made the human body, but left the final job of perfecting the body to us.
The midrash speaks of the male body, but its message applies equally to the female body. When human beings have children, we participate in creation just as God originally did. This is one of the most significant and Godly moments of our lives. As the Torah views it, both male and female bodies need perfecting before this can occur.