Mountain 1 of the twenty-four mountains (luopan) is Ren, one of the eight Heavenly Stems placed on the ring, occupying position N3, north sector, 337.5 to 352.5 degrees. Ren is Yang Water, and its classic image is the ocean, the great river, the flood. In Four Pillars astrology, where a person's chart is read from the stem and branch of the year, month, day and hour, a Ren Day Master, the stem governing the day of birth, is described as expansive, resourceful and bold, carving its own channels, though it can be inconstant or hard to pin down.
Ten Heavenly Stems exist in the full sexagenary system, one yang and one yin stem for each of the five elemental phases, but only eight reach the compass ring: the pair for Earth, Wu and Ji, is withheld from the perimeter and reserved to the centre, following the same five-phase logic recorded elsewhere in this atlas under which Earth's own direction is the pivot rather than any one of the eight compass points. Because ten stems and twelve branches do not share a common factor larger than two, a given stem does not return to a given branch until the combination has cycled sixty times, the sexagenary count (jiazi) that names years, months, days and hours across the traditional Chinese calendar; a mountain's own stem or branch name is therefore also, in a different context entirely, a recurring building block of that sixty-term cycle.