[Footnote 1:  The edition of Suarez’s “Disputationes” from which the following citations are given, is Birckmann’s, in two volumes folio, and is dated 1630.]

The title of this fifteenth Disputation is “De causa formali substantiali,” and the second section of that Disputation (to which Mr. Mivart refers) is headed, “Quomodo possit forma substantialis fieri in materia et ex materia?”

The problem which Suarez discusses in this place may be popularly stated thus:  According to the scholastic philosophy every natural body has two components—­the one its “matter” (materia prima), the other its “substantial form” (forma substantialis).  Of these the matter is everywhere the same, the matter of one body being indistinguishable from the matter of any other body.  That which differentiates any one natural body from all others is its substantial form, which inheres in the matter of that body, as the human soul inheres in the matter of the frame of man, and is the source of all the activities and other properties of the body.

Thus, says Suarez, if water is heated, and the source of heat is then removed, it cools again.  The reason of this is that there is a certain “intimius principium” in the water, which brings it back to the cool condition when the external impediment to the existence of that condition is removed.  This intimius principium, is the “substantial form” of the water.  And the substantial form of the water is not only the cause (radix) of the coolness of the water, but also of its moisture, of its density, and of all its other properties.

It will thus be seen that “substantial forms” play nearly the same part in the scholastic philosophy as “forces” do in modern science; the general tendency of modern thought being to conceive all bodies as resolvable into material particles and forces, in virtue of which last these particles assume those dispositions and exercise those powers which are characteristic of each particular kind of matter.

But the Schoolmen distinguished two kinds of substantial forms, the one spiritual and the other material.  The former division is represented by the human soul, the anima rationalis; and they affirm as a matter, not merely of reason, but of faith, that every human soul is created out of nothing, and by this act of creation is endowed with the power of existing for all eternity, apart from the materia prima of which the corporeal frame of man is composed.  And the anima rationalis, once united with the materia prima of the body, becomes its substantial form, and is the source of all the powers and faculties of man—­of all the vital and sensitive phenomena which he exhibits—­just as the substantial form of water is the source of all its qualities.