“Political Science in fact makes use of other practical sciences, even legislating what is to be done and what is not to be done. Its end, therefore, embraces the ends of the other practical sciences. For these reasons, then, this end will be the good of man.” Thus says Aristotle in the Nicomachean Ethics.
Commenting, however, on this passage, St. Thomas says “But we should note that he says political science is the most important, not simply, but in that division of practical sciences which are concerned with human things, the ultimate end of which political science considers. The ultimate end of the whole universe is considered in theology which is the most important without qualification.”
Now, Aristotle clearly discerned that man’s highest good was to approach, as much as possible, that of being like God. The god or the gods, however, are not concerned with practical things, but rather, contemplation. God himself could be said to be “thought thinking itself.” Just as clearly, Aristotle states that the ethical sciences are practical sciences. So Aristotle has a struggle with what man’s happiness consists in. It seems man wants to know the ultimate cause, but it also seems impossible to him. Therefore, at least in his ethics and political writings, he “lowers the standard” to what man is capable of: political science as the ultimate [achievable] human good.
Of course, Aristotle could not know of grace, and so that thing which could fill the gap between man’s unlimited desire for knowledge (“all men by nature desire to know”) and it’s possibility causes him to “settle” for something less.
For Dante, that settling less seems to be Limbo. The virtuous pagans who seek the good, as best they know it, but apart from grace, simply attain a state of not being tortured, but also never truly blessed.
Aristotle knew that man seeks not only to know about things, but about their causes. When we know a cause, we seek its cause as well. We are not satisfied until we know the ultimate cause, and even this we must truly know, and not just know of its existence. To know that there is a god (and to know many things ABOUT him) can be done through reason alone. To KNOW God is only a gift of grace. The virtuous pagans sought the highest good, perhaps even in Limbo still do. But they have no hope, being without the grace that can only come through the “Mighty One who descended here among us” to attain the beatific vision. They, rather, are “spared the fire and suffering of Hell” but suffer “one affliction only: without hope [they] live on in desire.”