The Lovers.
The Book of Thoth calls this card the twin of
Art. It says that this is primarily the card of division,
solve of the
solve et coagula alchemical maxim, associating it with swords, the instrument of division by which our intellect breaks problems down into their component parts. As such, it seems to associate naturally with
Chokmah and the pillar of
Mercy, despite its placement on the Tree as the path joining
Binah to
Tiphareth.
To see more about this card and its connections, read my thoughts about
Alchemy in the Tree.