The reason for selecting the human rather than the angelic nature for the hypostatic union is obvious from all that has preceded. Human nature is a microcosm, in which all grades of existence are summed up and represented. In taking human nature the Word assumes all created nature, from the lowest to the highest. For, although the angelic nature is superior to the human, it is only superior to it in certain respects, and not as a rational essence. Moreover, this superiority is part only temporary, enduring while the human nature is in the process of explication; and as to the rest, the inferiority of the human nature is counterbalanced by the supernatural elevation given to it in the hypostatic union, which raises the natural, human operation of the soul of our Lord Jesus Christ far above that of the angelic nature. Although, therefore, in the series of grades in the natural order of existence, the angelic nature is above the human, it is subordinated to it in the supernatural order, or the order of the incarnation, and in relation to the final cause. For it is through the human nature united to the divine nature in the person of the Word that the angelic nature completes its return to God and union with him. The elevation of created nature to the hypostatic union with God in the person of the Word introduces an entirely new principle of life into the intelligent universe. Hitherto, we have considered in the creative act a regular gradation in the nature of created existences, from the lowest to the highest. Each grade is determined to a certain participation in being superior in intensity to that of the one below it and to a mode of activity corresponding to its essence. There can be no grade of existence in its essence superior to the rational or intelligent nature, which is created in the similitude of that which is highest in the divine essence. No doubt, the specific and minor grades included under the universal generic grade of rationality might be indefinitely multiplied. As the angels differ from man, and the various orders of the angelic hierarchy differ from each other, so God might continue to create _ad infinitum_ new individuals or new species, each differing from all others, and all arranged in an ascending series, in which each grade should be superior in certain particulars to all below it. It is evidently possible that a created intelligence should be made to progress from the lowest stage of development continuously and for ever. Let us fix our thought upon the most distant and advanced limit in this progression which we are able to conceive. It is evident that God might have created an intelligent spirit in the beginning at that point, as the starting-point of his progression, and might have created at the same time other intelligent spirits at various distances from this point in a descending series. Suppose now that this is the case, and that the lowest in the scale