What are the motifs in We by Yevgeny Zamyatin?

Sex plays a central role in We because its regimentation is vital to the maintenance of social order. Free periods provided for in the Table of Hours can be devoted to sex behind lowered curtains, in accordance with the 300-year-old Lex Sexualis, which allows any Number to apply for a license to use any other Number(s) as a sexual product. The reason behind this legislation is that sex, a source of "stupid tragedies" in the past, ought to be the same kind of useful function as sleep, labor, and eating, Upon application, the Sexual Department determines a Number's optimal sexual days based on hormonal levels, enters these in the Table, and issues a pink checkbook. These checks are submitted to the house controller, who issues a permit to close the curtains. Polygyny and polyandry are both acceptable and theoretically cause no friction. O-90 is licensed to two long-time friends, D-503 and R-13. The bond between them is strengthened by the arrangement, but when the "triangle" is invaded by a fourth Number, I-330 whom D-503 favors, O-90 grows jealous and has D-503 stricken from her list.