This man or woman on the "cutting edge" of Jewish ritual, performs Judaism's oldest rite.
The first mohel was a 99-year-old ex-shepherd with no medical training whatsoever. There is no record of how he performed the procedure but, given that he was his own first subject, it is unlikely that Abraham used an anesthetic.
Things have changed since then. Circumcision is probably the best-known indication of Jewishness in a male (if not the most immediately visible!). It is also the oldest and one of the most widely followed of Jewish ritual practices. Abraham circumcised himself and his sons, Isaac and Ishmael; Zipporah circumcised Gershom, her first-born son. At first, like those estimable forebears, fathers and, apparently, occasionally mothers would circumcise their own sons, with a stone knife, usually of flint.
Through all the upheaval of conquering Canaan, building the Temple, being sent into exile in Babylon, and returning and rebuilding the Temple, the Jews still practiced circumcision. Gradually, it became the province of specially trained men, the mohelim, who were learned in the ritual elements surrounding the procedure (and probably no more ignorant of medicine than the average physician of the period). By the period of the Second Temple, they were using iron knives, and reciting the blessings that are still used today. Initially the brit was a family celebration, but with time it became a festivity that would involve the entire community. By the Middle Ages, the brit milah was usually performed in the synagogue, with the entire congregation active participants in the festivities.
Today, the mohel is considerably better trained than his historical antecedents. Or hers, as the case may be, as the non-Orthodox movements now certify women physicians for the role of mohelet (the female form of mohel). Historically, there were women who acted as circumcisers in medieval Italy and perhaps at other times in history. Today, there are mohalot (plural of mohelet) in the Reform and Conservative movements.
A mohel (or mohelet) is still trained in the ritual of circumcision according to the rules prescribed in classical rabbinic texts and subsequent law codes from the medieval period. However, today's mohel will also have been educated in modern surgical hygiene. The Reform movement in particular has taken an active interest in certifying mohelim who are doctors: They undergo training in the theology, history, and liturgy of the brit milah. A increasing number of Orthodox mohelim are also physicians.
Today's mohel will examine the baby to certify that he is healthy enough to undergo the procedure (unless a doctor has decided he cannot). If he is not, it must be postponed to a later date. As usual in matters of physical health, Judaism takes a cautious approach, and mohelim are generally more strict on this issue than doctors.