Libra begins at the autumn equinox — the moment day and night are equal. Only two signs open on a balancing event, and Libra is the one tipping towards the dark. That gives it a specific brief: define the balance before the scale starts to tilt. So Libra isn't indecisive, it's computing everyone's position, and the computation is more complex than it looks from outside.
You'll recognise it here: you can see both sides' logic and find both genuinely sound, so picking one isn't laziness — picking means giving up half the truth; awkwardness in a room produces physical discomfort in you, which is reflex rather than manners; and you rarely say no directly, you find a way for the other person to withdraw it themselves.
Running well, Libra is the one who gets a deal made: you can see a position both sides can stand on, and it's usually not either of the ones they came in with. That's invention, not compromise. Blocked, balance becomes absence — you take yourself off the scale so the two sides can level, and one day notice you're not in the picture. The tradition links Libra to Venus and to proportion, and proportion needs two ends: a scale with only one end isn't balanced, it's empty. So what Libra practises is putting itself back on. That isn't selfishness; it's giving the scale something to weigh.