Greek and Roman philosophy comprised the free efforts of reason to acquire a knowledge of first principles and the laws of nature, without a clear consciousness of the method most conducive to such attainments. The philosophy of the middle ages endeavored to attain the same end, but under the influence of a principle superior to itself, derived from revelation. In the course of transitional progress, it fell into a spirit exclusively dialectic, whence it emerged through fresh and independent exertions toward the discovery of fundamental principles. Thenceforth a combination of all human knowledge, in a more complete and systematic form, has tended with unfaltering success to explore, found, and define the principles of philosophy as a science. This, like every other element of cotemporaneous civilization, had its successive periods of origin, foundation, and development, stretching over a wide space, of which the twelfth century formed the middle line. Previous to that epoch, the various elements were disengaging themselves, and entering into a higher, as well as more practical amalgamation, which was destined rapidly to achieve the widest possible good. The early fathers of the Greek church went deeply into the current of oriental speculation, and they are worthy of special research, since so many golden grains of philosophy may be picked up in that sacred stream. It has already been shown, that by a range of imaginative reasoning, which soared far above the world of sense and outward experience, Plato sought a return to the supreme Godhead, infinitely exalted above all nature, deriving his chief proofs from immediate intuition and primeval revelation, or profound internal reminiscence. This fundamental tenet of the prior existence of the human soul was closely allied to the Indian doctrine of the metempsychosis, and, regarded in a literal sense, must be equally rejected by true Christian philosophy. But if we are to consider this Platonic notion of reminiscence under a more spiritual view, as the resuscitation of the consciousness of the divine image implanted in our souls, or the soul's perception of that image, this theory would then coincide with evangelical doctrine, and we ought not to wonder that this Platonic mode of thinking became the first great philosophy of revelation which was fashioned and promulgated in a mediæval form. It was most adapted to captivate the profoundest Christian thinkers, and pour a sweet solace into their aspiring hearts; hence, the prevalency of this system in the schools, until the end of the twelfth, and the beginning of the thirteenth century. Many leading minds even believed that they discovered in it the types of their own religious views. The symbolical fancies of Timæus respecting physical phenomena, were taken up with spirit, and erroneous ideas respecting the laws of creation long prevailed, although the mathematicians of Alexandria had demonstrated their fallacies.