from the Notes section of "Bouma Shapes":

"The theory developed by Saint Thomas in his short treatise on halos is instructive in this regard. The beatitude of the chosen, he argues, includes all the goods that are necessary for the perfect workings of human nature, and therefore nothing essential can be added. There is, however, something that can be added in surplus (superaddi), an 'accidental reward that is added to the essential', that is not necessary for beatitude and does not alter it substantially, but simply makes it more brilliant (clarior). The halo is this supplement added to perfection - something like the vibration of that which is perfect, the glow at its edges."
- Giorgio Agamben, The Coming Community, 54-55