Circumcision
Circumcision is very important to most branches of Judaism, with over 90% of male adherents having the procedure performed as a religious obligation. The basis for its observance is found in the Torah of the Hebrew Bible, in Genesis chapter 17, in which a covenant of circumcision is made with Abraham and his descendants. Jewish circumcision is part of the "brit milah" ritual, to be performed by a specialist ritual circumciser, a "mohel", on the eighth day of a newborn son's life, with certain exceptions for poor health. Jewish law requires that the circumcision leaves the glans bare when the penis is flaccid. Converts to Conservative and Orthodox Judaism must also be circumcised; those who are already circumcised undergo a symbolic circumcision ritual. Circumcision is not required by Judaism for one to be considered Jewish, but some adherents foresee serious negative spiritual consequences if it is neglected.
History of male circumcision
The 1st-century Jewish author Philo Judaeus (20 BCE - 50 CE) defended Jewish circumcision on several grounds, including health, cleanliness and fertility. He also thought that circumcision should be done as early as possible as it would not be as likely to be done by someone's own free will. He claimed that the foreskin prevented semen from reaching the vagina and so should be done as a way to increase the nation's population. He also noted that circumcision should be performed as an effective means to reduce sexual pleasure: "The legislators thought good to dock the organ which ministers to such intercourse thus making circumcision the symbol of excision of excessive and superfluous pleasure." There was also division in Pharisaic Judaism between Hillel the Elder and Shammai on the issue of circumcision of proselytes.