Supposing this interpretation to be admissible, the Scottish school, after all, must modify its doctrine that we know things directly and immediately; for as in external things light is necessary as the medium of vision, why should not an intelligible light be necessary as the medium of the intellectual apprehension of intelligibles? Now, as this light has in it the similitude of the things apprehensible by it, and is for that same reason light to our understanding, it may, as Plato held, very properly be expressed by the word _idea_, which means likeness, image, or representation. The error of Plato would not then be in holding that we know only _per ideam_ or _per similitudinem_, but in confounding creator and creature, and recognizing nothing except the idea either to know or to be known. On this interpretation, the light may be identical with the object, or it may not be. Being is its own light, and is intelligible _per se_; objects distinguishable from being are not, and are intelligible only in the light of being, or a light distinguishable from themselves. {152} As being in its full sense is God, we may say with Malebranche that we see all things in God, but must add, _and by the light of God_, or _in Deo et per Deum_. Assuming ideas as the light by which we see to be the real doctrine of the scholastics, we can readily understand the relation of ideas to the peripatetic categories or praedicaments, or forms under which all objects are and must be apprehended, and thus connect the old quarrel of the philosophers with their present quarrel. The categories, according to the Platonists, are ideas; according to the peripatetics, they are the forms of the _mundus logicus_, which, as we have seen, they distinguish from the _mundus physicus_. The Scottish school having demolished this _mundus logicus_, by exploding the doctrine of intermediary ideas which compose it, if we take that world as formal, and fail to identify it with the divine light, the question comes up, Are the categories or self-evident truths which precede all experience, and without which no fact of experience is possible, really objective, or only subjective? The question is, if we duly consider it, Is the light by which we see or know on the side of the subject or on that of the object? Or, in other words, are things intelligible because we know them, or do we know them because they are intelligible? Thus stated, the question seems to be no question at all; but it is made a very serious question, and on the answer to it depends the validity or invalidity of St. Anselm's argument.