"If the very essence of knowledge changes, at the moment of the change to another essence of knowledge there would be no knowledge, and if it is always changing, there will always be no knowledge, and by this reasoning there will be neither anyone to know nor anything to be known. But if there is always that which knows and that which is known —if the beautiful, the good, and all the other verities exist— I do not see how there is any likeness between these conditions of which I am now speaking and flux or motion."