The object of the old metaphysical theology was to see how far unassisted reason could go in the knowledge of God. Certainly a reason-derived knowledge of God is the highest problem of philosophy. The earliest teachings of religion are figurate conceptions of God. These conceptions, as the Creed arranges them, are imparted to us in youth. They are the doctrines of our religion, and in so far as the individual rests his faith on these doctrines and feels them to be the truth, he has all he needs as a Christian. Such is faith: and the science of this faith is Theology. But until Theology is something more than a bare enumeration and compilation of these doctrines _ab extra,_ it has no right to the title of science. Even the method so much in vogue at present--the purely historical mode of treatment--which for example reports what has been said by this or the other Father of the Church--does not invest theology with a scientific character. To get that, we must go on to comprehend the facts by thought,--which is the business of philosophy. Genuine theology is thus at the same time a real philosophy of religion, as it was, we may add, in the Middle Ages. And now let us examine this rational theology more narrowly. It was a science which approached God not by reason but by understanding, and, in its mode of thought, employed the terms without any sense of their mutual limitations and connexions. The notion of God formed the subject of discussion; and yet the criterion of our knowledge was derived from such an extraneous source as the materialised conception of God. Now thought must be free in its movements. It is no doubt to be remembered, that the result of independent thought harmonises with the import of the Christian religion:--for the Christian religion is a revelation of reason. But such a harmony surpassed the efforts of rational theology. It proposed to define the figurate conception of God in terms of thought; but it resulted in a notion of God which was what we may call the abstract of positivity or reality, to the exclusion of all negation. God was accordingly defined to be the most real of all beings. Any one can see however that this most real of beings, in which negation forms no part, is the very opposite of what it ought to be and of what understanding supposes it to be. Instead of being rich and full above all measure, it is so narrowly conceived that it is, on the contrary, extremely poor and altogether empty. It is with reason that the heart craves a concrete body of truth; but without definite feature, that is, without negation, contained in the notion, there can only be an abstraction. When the notion of God is apprehended only as that of the abstract or most real being, God is, as it were, relegated to another world beyond: and to speak of a knowledge of him would be meaningless. Where there is no definite quality, knowledge is impossible. Mere light is mere darkness.