  Philosophically, Plotinus argued that postulating Forms without a superordinate principle, the One, which is virtually what all the Forms are, would leave the Forms in eternal disunity.  If this were the case, then there could be no necessary truth, for all necessary truths, e.g., 3 + 5 = 8, express a virtual identity, as indicated here by the ‘=’ sign.  Consider the analogy of three-dimensionality and solidity.  Why are these necessarily connected in a body such that there could not be a body that had one without the other?  The answer is that body is virtually three-dimensionality and virtually solidity.  Both three-dimensionality and solidity express in different ways what a body is.