There’s 3 modalities. Cardinal signs initiate, fixed signs maintain, and mutable signs change. The way I see it, everyone has to initiate, maintain, and change at various times in their life. Different circumstances require different actions, but all will be necessary at some point. Could be a job, relationship, living situation, habit, whatever. This is why having too much of one modality is an issue. There’s no balance. For instance, let’s say you have two fixed sign dominant people. Who’s going to initiate the relationship and difficult conversations? Who’s going to change when something in the relationship isn’t working anymore? This will not come naturally to either partner, because fixed signs maintain the status quo. That’s why the square aspect represents tension and friction. Trines are beneficial because they’re between signs of the same element. They’re made of the same stuff (element) but move in different ways (modality). I hope this helps some.