Fervor represents thought's capacity as a stepwise activity.  When one follows through, executes, applies the principles arrived at by catharsis - new necessities appear.  And in principle the new necessities are able to undermine the very principles that made them visible.  This can't happen on its own, though - it requires a procedure.   The exercise of the reasoning faculty, a sort of invisible muscle, is required - and this activity includes affective and ethical components.   With fervor the line between thought and life is very thin, in part because it makes use of aspects of them both that we do not yet understand