The Speaker has no interest in Glimmer, Marks, or the other currencies of the Tower's military functions. But he happily accepts these Motes, points of Light willed into being by an exercise of a mighty Guardian's power.
Some say they will one day become the souls of new Ghosts. Others believe they feed the intricate machinery that the Speaker tends. Whatever the case, the Speaker will happily reward donors with patterns and signs from his collection - more out of gratitude than any mercantile impulse.