- Being is perfection. Any being, then, that is not infinite in its being or perfection must contain within itself some principle by which it is finite and limited. This principle, though, cannot be the being through which something is perfected since perfection is, of itself, infinite and unlimited. Perfection is opposed to limitation, so our limiting principle must be something else. Its name is potency.
- Potency requires the act of being in order to become actual. All potencies are potencies for some act. In this way, potency has an essential relationship to act. Act, however, bears no essential relationship to potency.
- Something is known only inasmuch as it is in act. Being-in-act is determinate and therefore intelligible. Potency is essentially indeterminacy, it is not yet determined to an act. As such, it is unintelligible. Our knowledge of potency, then, cannot come to us through itself but only through our knowledge of something which is intelligible: act.
Parmenides saw the undifferentiated nature of being. Being is not differentiated within itself, so inasmuch as things are said to be, there can only be one being. Any distinction between things must be predicated upon something other than being, but the only thing besides being is non-being, which is literally nothing. At this point, if we have no adequate response, we should cease thinking or speaking, for our metaphysics and thus all true knowledge, is complete.