Square
The square is the aspect formed when two planets sit ninety degrees apart, a quarter of the way around the chart.
The square is the aspect formed when two planets sit ninety degrees apart, a quarter of the way around the chart. The two signs share a modality but belong to different elements, so the planets work at the same tempo while pulling in directions that do not agree. Tradition counts the square as hard, and it does bring friction: two parts of the self that catch on each other rather than cooperate.
That friction is the point. A square is the most productive kind of difficulty, because the discomfort will not sit still and demands a response. Mars square Saturn feels like pressing forward and hitting a wall at once, effort met by delay until persistence wins something solid. Venus square Mars sets tenderness against raw wanting, affection that keeps tripping over its own impatience. Much of a person's drive and growth comes from working a square until both planets get used instead of one silencing the other.
A square is often where a chart's real work sits, a friction a person keeps meeting until they deal with it. Its work is to stop letting one side win and build something that carries both.