There are two marriages that Tristan needs to make. The first marriage is an inner marriage with his own soul, with Iseult the Fair. That marriage is made by going to the inner world, practicing his religion, his inner work, living with the gods of the inner world. The second marriage is to Iseult of the White Hands. This marriage means a union with another human being, and it means taking her as a human being. It also means making other relationships—making friends—and taking them as human beings.
