Mishnah 18 - Chapter 3 - Pirkei Avot

R. Eliezer ben Chisma says: Kinin [bird-offerings (from "kan tzippor," a bird's nest). There are weighty halachoth pertaining to them, such as a mandatory offering being mixed up with a gift-offering; or a burnt-offering, whose services are "above," being mixed up with a sin-offering, whose services are "below"], and pithchei niddah [the halachoth of a niddah who has lost track of her menstrual time and must be vigilant to determine its onset (Sometimes she must immerse herself ninety-five times, according to the view that immersion in its prescribed time is a mitzvah)] — [kinin and pithchei niddah] are the foundation of halachoth (the oral law), [for which reward is received.] Tekufoth [the movements of the constellations] and gematrioth [the numeration of the letters] are the "seasonings" of wisdom, [like those which it is customary to eat at the end of a meal for dessert. So, these wisdoms honor their possessors in the eyes of men.]