Most of your “strongest” mages visit or know about Naclos and what it means to be a gray mage. Should all mages in the world of Recluce attempt to become gray in order to gain strength, live longer, and influence others?

The short answer is no. Initially, all mages have a tendency toward being either black or white, but some are so firmly oriented toward one extreme or the other that attempting to move toward “grayness” would destroy them. Consider the results of the trials that all full druids must undergo and the fact that many do not survive such trials.