Square, in full
Three signs is a quarter of the wheel. Modality repeats every three signs, so a square always joins two signs of the same mode, either two cardinal, two fixed or two mutable. Element repeats every four, so a three-sign gap moves the element by three places and can never land on the complementary partner. Fire meets water or earth, air meets water or earth, and the classical pairings of fire with air and earth with water are the two combinations a square cannot produce.
Ptolemy puts the square, which he calls the quartile, with the opposition among the disharmonious aspects. The picture is of two drives that fire at the same moment and pull in different directions, since the shared modality means both want to act at the same stage of things. Traditional texts read the square as the friction that forces development, and modern astrologers often describe a chart with no squares in it as short of pressure rather than fortunate.
Each sign has exactly two squares, one three signs ahead and one three behind, so the wheel produces twelve square pairings in total. The compatibility pages here score a square 2 out of 5. That number comes from the angle rather than from anything written about the two signs involved, which is why every square pairing carries it.
- Astrology
- Nothing else in common use
A worked example
Aries, Cancer, Libra and Capricorn are the four cardinal signs, spaced 90 degrees apart. Aries squares Cancer and Capricorn and opposes Libra. In elements that reads as fire against water and fire against earth for the two squares, and fire against air for the opposition. The fixed signs and the mutable signs repeat the same shape, one quarter-turn at a time.
Sources
Ptolemy groups the quartile (square) with the opposition as the disharmonious aspects, against trine and sextile as harmonious.
Ptolemy, Tetrabiblos I.13, "Of the Aspects of the Signs" (Loeb translation, LacusCurtius)
See also
Where it comes up on this site
Square: frequently asked
The two sharing your modality but not your element, three signs away either side. Taurus squares Leo and Aquarius; Gemini squares Virgo and Pisces.
Hard, not bad, in the traditional vocabulary. Two parts of a chart want to act at the same moment in ways that will not fit together, and the grinding that follows is what the tradition credits with forcing development. Charts holding no squares at all get described as lacking a push rather than as lucky, which tells you how the reading is meant.