Who knows two hundred thirty-one?
Please cite/link your sources, if possible. At some point at least twenty-four hours from now, I will:
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Sefer Yetzirah (2:4 passim) speaks of 231 "gates," each with an obverse and a reverse, formed by the letters of the Alef-Beis - i.e., the number of possible combinations of two different letters.
(There are 22 letters, so combining each of them with each of the others yields 22 x 21 = 462 combinations. Half of these, 231, are the reverses of the other half - e.g., אב and בא.)
Siman 231 in S.A. O.C. is about the halachic obligation that everything a person does should be l'shem shamayim (for the sake of Heaven). That means that eating, drinking, sleeping, etc. (anything that is neither obligatory nor forbidden by the Torah) should only be done if it will help one better serve Hashem (i.e., be healthy in order to do mitzvot). If one eats only because the food tastes good, or to fulfill sinful gluttonous cravings beyond that of normal hunger, then it is forbidden to eat. Eating food that tastes good can also be l'shem shamayim because it will put you in a good mood.