Defining a great thinker

If a thinker were able to best both Saint Thomas Aquinas and Friedrich Nietzsche, and their followers, that thinker would need a big ego to make such a claim, even if it turns out to be true. Perhaps a large ego is part of such a thinker?

The question then usually arises, is that claim the claim of a mad fool or a great genius? One would have to also be a fool or a genius to make the judgment about the fool/genius.

Does courage come before such a large ego? If Aristotle was right in saying that courage is the medium between rashness and cowardice then some form of reason seems to decide the courage, which would balance the fool and the genius.

So can we now say that a great thinker has a large ego with great courage? If so then genius seems to be preceded by theses traits, followed by reason. If one of these traits is missing we seem to have a less than great thinker. How much of this is nature and how much is nurture? Nature seems to lead, but such an unusual nature needs nurturing, and it will probably be an unusual nurturing.