That which is eternally perfect begets eternally, and that which it begets is eternal, but inferior to the generating principle.
EnneadV, book I, 13–15
What is to be understood by these words of Plotinus is that the one (which could be likened to God, since the one is divine, or to the “universal Being”) is both eternal and perfect. What he begets is also eternal, but is a degraded version of his divinity. He always begets something less than himself.
Let us open a parenthesis to recall that in Plotinus, souls participate in the divine essence, since they are begotten by the. One, but they“have degraded themselves by forgetting their origin“. (Ennead
This means that they no longer perceive God as their true and perfect origin, their attention is focused on other objects, and consequently they no longer see their true nature.