Suppose there is a first cause (i.e. a first, uncaused member of a causal series) of all caused reality. This being clearly has some degree of power. Otherwise it could not have caused all of causal reality. To avoid the conclusion that it has some aribtrary degree of power, a conclusion which is problematic because the arbitrary limit in power is not externally caused and thus difficult to explain, we might want to say that the power of the first cause is maximal. But if the first cause has maximal power, then, arguably, the first cause is perfect. One way of reasoning to this conclusion is roughly as follows:

1. The first cause has maximal power.
2. Maximal power is the least limited form of possible power.
3. The (possible) power to be completely perfect is less limited than the (possible) power to be (partially) imperfect.
4. If (2) and (3), then maximal power includes the power to be completely perfect.
5. Only a completly perfect being is able to be completely perfect.
6. Therefore, the first cause is completely perfect.