the essence of in-betweenness

All effective performances share this “not-not not” quality.  Performer training and workshops focus their techniques not on making one person into another but on encouraging the performer to act in-between identities; in this sense, performing is a paradigm of liminality.  And what is liminality but literally the “threshold,” the space that both separates and joins spaces: the essence of in-betweenness?