At which exact moment does a child 
become an adult? Since some people never reach psychological adulthood (such as 
the bozos who honk and holler when they lose out on a parking spot), physical 
maturity was chosen as the mark of adulthood for all. Puberty generally begins 
in the early teen years, thus bar mitzvah age was set at thirteen years plus one 
day. 
Since this doesnt fully explain why thirteen is the chosen year, midrashic 
sources credit Moses with choosing age thirteen as the bar mitzvah year. There 
are other instances that Moses is said to have spoken the nature of Jewish 
practice at Sinai without jotting it down in the Torah. For example, Moses 
described how tefillin should look as their appearance is not described in the 
Torah. Jews have been wearing uniform-looking leather boxes ever since. 
Special emotional maturity enough to be regarded as a bar mitzvah, according to 
at least one halachic opinion. Specifically, a boy who lost a parent would be 
eligible for his bar mitzvah anytime after his twelfth birthday. (Girls 
traditionally reached bat mitzvah at age twelve.) A child who loses a parent 
reckons with adulthood early on.
Other cultures avoid the number thirteen. Witch covens, apparently, form around 
the presence of twelve practitioners plus the devil, because black magic thrives 
on this number. Fear of the number thirteen pervades our culture, and even has a 
phobia associated with it. Skyscrapers are sometimes built without a thirteenth 
floor. Street numbers would be set to skip the address thirteen (the old 
television show The Munsters featured a monster family who lived at 1313 
Mockingbird Lane at the fictional Muckingbird Heights.
Judaism regards the number thirteen differently. Thirteen denotes positive 
attributes in the age of a boy, in moral conduct, and in the tenets of faith in 
God. For example: 
		 A Jewish male child transitions to adulthood at Thirteen.
		 God is said to have thirteen attributes of mercy. (Exodus 34:6-7) 
		 Maimonides, a twelfth century Torah philosopher, scholar who was a 
court physician on the side, ascribed thirteen principles to the Jewish faith.