Opinion and knowledge, then, having distinct objects, must also be distinct faculties.

And by faculties I mean powers unseen and distinguishable only by the difference in their objects, as opinion and knowledge differ, since the one is liable to err, but the other is unerring and is the mightiest of all our faculties.

If being is the object of knowledge, and not-being of ignorance, and these are the extremes, opinion must lie between them, and may be called darker than the one and brighter than the other.

This intermediate or contingent matter is and is not at the same time, and partakes both of existence and of non-existence.

Now I would ask my good friend, who denies abstract beauty and justice, and affirms a many beautiful and a many just, whether everything he sees is not in some point of view different--the beautiful ugly, the pious impious, the just unjust?
Is not the double also the half, and are not heavy and light relative terms which pass into one another?
Everything is and is not, as in the old riddle--'A man and not a man shot and did not shoot a bird and not a bird with a stone and not a stone.' The mind cannot be fixed on either alternative; and these ambiguous, intermediate, erring, half-lighted objects, which have a disorderly movement in the region between being and not-being, are the proper matter of opinion, as the immutable objects are the proper matter of knowledge.