Mountain 3 of the twenty-four mountains (luopan) is Gui, one of the eight Heavenly Stems placed on the ring, occupying position N1, north sector, 7.5 to 22.5 degrees. Gui is Yin Water, and its classic image is the dew, the mist, the gentle rain. In Four Pillars astrology, where a person's chart is read from the stem and branch of the year, month, day and hour, a Gui Day Master, the stem governing the day of birth, is described as subtle, pervasive and imaginative, though it may be timid, moody or inclined to withdraw rather than assert.
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.