Then for a moment we see. These are the moments of intuition. They are not divorced from the normal ways of understanding, but permeate them and on occasion, lead them in unexpected directions. It is this intuition that according to Maritain makes the metaphysician. No intuition, no metaphysician.
Some concrete event triggers the intuition.
The other, and probably much rarer, is by way of judgment. The strength of our reasoning leads us inexorably to a peak of tension that is resolved by a moment of insight. If our sight has been dulled by too long an exposure to the fact of existence, then something must come along to shake us loose and make us really see what is in front of our eyes. Our ordinary experience must be magnified so that existence appears before us with its original face. Maritain suggests that there are various paths that can lead to this intuition.