Bi Jian shares the same element and polarity as the Day Master — the mirror of self: friends, peers, competitors, and one's own drive for independence.
When Bi Jian is strong and revealed, self-assertion and sociability are both high. For a weak Day Master it is support; for a strong one it becomes rivalry and wealth-sharing. Its pillar position shows where support comes from — early years, peers, the spouse palace, or later life.