Air and earth think differently: one lives on ideas and motion, the other on results and consistency. With respect, they complete each other — one's ideas land thanks to the other. Without it, one feels tied down and the other dizzy. Translation is the key.
One initiates (cardinal), the other sustains (fixed): done well, it's the formula for projects that start AND finish. Done badly, one pushes change and the other digs in. Negotiation is this bond's muscle.