Trine and Square

A trine joins signs in the same triangle, that is, the same element group: fire is Aries, Leo and Sagittarius; earth is Taurus, Virgo and Capricorn; air is Gemini, Libra and Aquarius; water is Cancer, Scorpio and Pisces. Each pair within a group is four signs, 120 degrees, apart.

Astrology today often reads it as two forces that get on naturally, with no effort. With the Moon trine Venus, for example, how you look after yourself and what you enjoy fit well, so when you relax you are naturally doing something you like.

A more useful question than “smooth”: are these two forces so easy together that you have never practised the other way?

What the old texts say: Book I ch. 13 of Ptolemy's Tetrabiblos gives the trine one and a third right angles, four signs and 120 degrees, and calls trine and sextile harmonious because they join signs of the same kind — all masculine or all feminine. Ch. 18 adds that the zodiac is split into four equal-sided triangles, the first through Aries, Leo and Sagittarius — exactly four signs apart from each other.

Astrology today often reads a square as needing effort to make two things work together. Take Aries (fire) square Cancer (water): one wants to charge ahead, the other to look after feelings first; both want to lead, so they take turns giving way or find a new way through.

A practical view: a square is often where a person really builds a skill, because it pushes them to handle two different approaches. The longer it catches, the more solid the skill it tends to build.

Ask yourself: in you, is it a place worth practising? Is there something that felt awkward at first and later became one of your strengths?

What the old texts say: the same chapter gives the square one right angle, three signs and 90 degrees, and puts it with opposition among the ones that are not harmonious, again because the signs it joins are of different kinds. The text also explains the angles with musical ratios: apply a half to opposition and you get the square.

Any aspect can be read with two questions: do the two forces run smoothly, and have you ever practised the other way? For a trine the first answer is usually “smoothly,” so watch the second; for a square the first is usually “it catches,” but the answer to the second is often where your skill lies.

What this app does: aspects are computed and listed as they are, each shown the same way, so you can hold them up to these two questions yourself.

What the old texts say: Book I ch. 13 is clear about what harmonious and not harmonious rest on — whether the signs joined are of the same kind, using the masculine and feminine sorting of ch. 12. Trine and sextile are harmonious; square and opposition are not.