Element, in full
The groups are fixed and never overlap. Fire covers Aries, Leo and Sagittarius. Earth covers Taurus, Virgo and Capricorn. Air covers Gemini, Libra and Aquarius. Water covers Cancer, Scorpio and Pisces. Each set is called a triplicity, because its three signs sit at the corners of an equilateral triangle drawn inside the zodiac wheel, 120 degrees apart, which is also the angle astrologers call a trine.
The scheme arrives from Greek natural philosophy, where the four elements were the physical constituents of everything below the Moon, each defined by a pair of qualities: fire hot and dry, air hot and moist, water cold and moist, earth cold and dry. Hellenistic astrologers mapped that onto the signs and kept the pairings. Modern popular readings translate the qualities into temperament, describing fire as active, earth as practical, air as verbal and water as feeling-led.
Element does most of the work in compatibility writing. Fire with air and earth with water are the combinations tradition treats as complementary, which is why both the sextile and the opposition land on them, while the square lands on the combinations it does not. None of this has been measured against outcomes, and astrologers disagree among themselves about how much weight a Sun sign's element deserves once the rest of a chart is on the table.
- Astrology
- Triplicity
A worked example
Aries, Leo and Sagittarius are the fire triplicity. They occupy positions 1, 5 and 9 on the wheel, four signs apart in each step, and four signs is 4 x 30 = 120 degrees. Join them and you get an equilateral triangle. The other three elements produce three more triangles of the same size, and between them the four triangles touch all twelve signs exactly once each.
Sources
Aristotle paired the four Greek elements with opposed qualities: fire hot and dry, air hot and wet, water cold and wet, earth cold and dry.
Wikipedia — Classical element
See also
Where it comes up on this site
Element: frequently asked
Fire: Aries, Leo, Sagittarius. Earth: Taurus, Virgo, Capricorn. Air: Gemini, Libra, Aquarius. Water: Cancer, Scorpio, Pisces. Read round the wheel from Aries and the four simply repeat, which is why any two signs four apart share an element.
No. Element repeats every four signs and modality every three, so they cut the wheel in different directions. Four times three gives twelve combinations, one per sign, which is how Taurus ends up the only fixed earth sign.