The “material substantial forms” are those which inform all other natural bodies except that of man; and the object of Suarez in the present Disputation, is to show that the axiom “ex nihilo nihil fit,” though not true of the substantial form of man, is true of the substantial forms of all other bodies, the endless mutations of which constitute the ordinary course of nature.  The origin of the difficulty which he discusses is easily comprehensible.  Suppose a piece of bright iron to be exposed to the air.  The existence of the iron depends on the presence within it of a substantial form, which is the cause of its properties, e.g. brightness, hardness, weight.  But, by degrees, the iron becomes converted into a mass of rust, which is dull, and soft, and light, and, in all other respects, is quite different from the iron.  As, in the scholastic view, this difference is due to the rust being informed by a new substantial form, the grave problem arises, how did this new substantial form come into being?  Has it been created? or has it arisen by the power of natural causation?  If the former hypothesis is correct, then the axiom, “ex nihilo nihil fit,” is false, even in relation to the ordinary course of nature, seeing that such mutations of matter as imply the continual origin of new substantial forms are occurring every moment.  But the harmonization of Aristotle with theology was as dear to the Schoolmen, as the smoothing down the differences between Moses and science is to our Broad Churchmen, and they were proportionably unwilling to contradict one of Aristotle’s fundamental propositions.  Nor was their objection to flying in the face of the Stagirite likely to be lessened by the fact that such flight landed them in flat Pantheism.

So Father Suarez fights stoutly for the second hypothesis; and I quote the principal part of his argumentation as an exquisite specimen of that speech which is a “darkening of counsel.”

“13.  Secundo de omnibus aliis formis substantialibus (sc. materialibus) dicendum est non fieri proprie ex nihilo, sed ex potentia praejacentis materiae educi:  ideoque in effectione harum formarum nil fieri contra illud axioma, Ex nihila nihil fit, si recte intelligatur.  Haec assertio sumitur ex Aristotele 1.  Physicorum per totum et libro 7.  Metaphyss. et ex aliis authoribus, quos statim referam.  Et declaratur breviter, nam fieri ex nihilo duo dicit, unum est fieri absolute et simpliciter, aliud est quod talis effectio fit ex nihilo.  Primum proprie dicitur de re subsistente, quia ejus est fieri, cujus est esse:  id autem proprie quod subsistit et habet esse; nam quod alteri adjacet, potius est quo aliud est.  Ex hac ergo parte, formae substantiales materiales non fiunt ex nihilo, quia proprie non fiunt.  Atque hanc rationem reddit Divus Thomas I parte, quaestione 45, articulo 8, et quaestione 90, articulo 2, et ex dicendis magis explicabitur.  Sumendo ergo ipsum fieri