A reflection on the knowledge we have, that is, knowing that we know, so increases our knowledge that the new knowledge relates to the former in the way that more relates to less, or even the infinite to the finite. With reflective knowledge we rule and control direct knowledge as we will; only reflective knowledge brings direct knowledge under our free will. We would never have discovered the art of writing if we had not reflected on language. Numbers are an invention arising from reflection on the ideas of numbers. Algebraic letters are the result of a reflection on numbers. Analytical functions arose from a third reflection on algebraic letters. This is the real meaning of the apparent play on words: 'we know that we know that we know'! It is the simplest formula expressing the order of ideas, to which the Analytical Functions of Lagrange belong.
[Antonio Rosmini, Certainty, Cleary & Watson, trs., Rosmini House (Durham: 1991), p. 111n131.]