He illustrates this by the comparison of a sight-presentation, which has also a twofold subject, the one subject being the thing outside the soul, the other the visual faculty. But this answer cannot stand. For it is impossible that the action and perfection of the eternal should depend on anything temporal. But phantasms are temporal things, continually springing up afresh in us from the experience of the senses. Therefore the intellectual impressions, whereby the potential intellect is actuated and brought to activity, cannot possibly depend on phantasms in the way that visual impressions depend on things outside the soul.
Nothing receives what it has already got.
Therefore, on this showing, no impressions from our phantasms are received in the potential intellect. G.6 and 7. If the potential intellect receives no intellectual impressions from the phantasms that are in us, because it has already received them from the phantasms of those who were before us, then for the like reason we must say that it receives impressions from the phantasms of no generation of men, whom another generation has preceded. But every generation has been preceded by some previous generation, if the world and human society is eternal, as Averroists suppose. For the potential intellect, like every other substance, operates according to the mode of its nature.