If being is understood as power directed toward bringing itself to appearance and, therefore, as presenting a unity of good and true in the senses discussed in essay 2 above, then the character of this unity becomes an important problem. This unity is in the first instance the unity which Aristotle said was convertible with being. But this convertibility does not entail identity, for there are many kinds of unity and unities of unities. The Parmenides is devoted to unraveling these matters. This famously difficult dialogue has been carefully analyzed and discussed by Robert Brumbaugh. I can think of no better way of getting into the topic than through a consideration of his very thorough study in Plato on the One.¹