Sallustius, Sallust On the Gods and the World…
“ For the number nine, which is generated from the first perfect number, (that is, three) is, through similitude and sameness, accommodated to the multiform causes of the mundane order and harmony; all of them at the same time being collected into one summit for the purpose of producing one consummate perfection; for the Muses generate the variety of reasons with which the world is replete; but Apollo comprehends in union all the multitude of these. And the Muses give subsistence to the harmony of soul; but Apollo is the leader of intellectual and indivisible harmony. ”
