The eighth day is the Torah's specified time. It overrides Shabbat and Yom Kippur — the mitzvah takes precedence.
Question 2
Who is primarily obligated to circumcise a baby boy?
The father bears the primary obligation. He may hire a mohel to perform it, but the mitzvah is the father's. If he doesn't act, the beit din (court) must arrange it.
Question 3
If two of a woman's sons died from circumcision, what happens with the third?
The Rambam rules: after two brothers died from circumcision, the third is not circumcised. This is a remarkable early recognition of hereditary bleeding disorders.
Question 4
A baby boy is born already without a foreskin. Is any procedure needed?
Even without a foreskin, hatafat dam brit is required — a symbolic drop of blood representing the covenant. The covenant requires a human act, not just a physical state.
Question 5
What penalty does the Torah assign for willful failure to be circumcised as an adult?
Karet — one of only 36 transgressions carrying this penalty. The severity reflects circumcision's centrality to the Abrahamic covenant.