"Summa Theologiæ" (Sum of Theology) and hardly be missed. Yet, arrogant as this encyclopedic comprehensiveness now seems, there was really nothing else to be done. Mathematics was the only one of the natural sciences which had succeeded in disengaging itself from theology; there was no social science, no independent science even of politics; there was no history other than ecclesiastical; and (what concerns us here) there was no science of man. Man was not yet a unit in the creation, and inquiries concerning him were properly included in Cosmology, which is pagan for Theology. "Naturam autem," says Thomas, "hominis considerare pertinet ad Theologum ex parte animæ"[1] (It is the theologian's province to consider man's nature on the soul's side). The theologus kept hold of the nature of man till Descartes had emancipated him from his serfdom; but to him and his theological science—our statical factor—we may justly ascribe that first successful raising of the problem of human individuality which made possible, as we shall see, its establishment and utilization under the influence of the dynamical factor—physical science.
The fostering aid of Theology to Psychology does not, however, end when the latter is able to walk alone. All great questions subsequently raised, the settlement of which by physical methods marks each fresh stage, issue from the theological incunabula (cradle) where the science was reared. A history of the embryogeny of ideas would demonstrate that ideas which were afterward properly philosophical were at first purely theological. The idea of the infinite, at first negative, was made positive, through being made theological, by the Greek Fathers. Prof. Jevons believes that his "Law of Simplicity," though almost unnoticed in modern times, was known to Boëthius, and he adds:
"Ancient discussions concerning the doctrine of the Trinity drew more attention to subtle questions concerning the nature of unity and plurality than has ever since been given to them."[2]
With greater emphasis, which, however, only exaggerates an important truth, it has been said that the doctrine of the Trinity is the "foundation of all the metaphysical thought and speculation of the ages after Gregory the Great."[3] This will be sufficiently near the mark if the honor is shared with the dogma of Transubstantiation after, say, the "captivity" at Avignon. In more recent times, especially in Germany in the first half of the present century, the doctrine of the Incarnation has been the "motive" of various metaphysical developments.
In Psychology the final cause of Locke was theological; for the rise of an a priori philosophy in Herbert of Cherbury was theological, and it was to overthrow apriorism that Locke undertook his examina-
