Men can be in one of two states:

When we don't know things, we're humble, because we feel ignorant and want to learn and understand stuff.

When we understand it, we are arrogant, because we think that we are really smart and therefore superior to others...

But to achieve greatness, we need to be in both states simultaneously. Humbleness and interest to learn will assure constant progress, while arrogance and pride will force us into unknown in pursuit of greatness.