Secondly, the word “matter” is used for _the potential term lying under the substantial form_ by which it is actuated. In this sense the matter is a _metaphysical_ reality which, by completing its substantial form, concurs with it to the constitution of the physical being--that is, of the substance. It is usually called _materia formata_, or “formed matter.” Thirdly, the word “matter” is used also for _the potential term of substance conceived as deprived of its substantial form_. In this sense the matter is a mere potency of being, and therefore _a being of reason_; for it cannot thus exist in the real order: and it is then called _materia informis_, or “unformed matter.” It is, however, to be remarked that the phrase _materia informis_ has been used by the fathers of the church to designate the matter as it came out of the hands of the Creator before order, beauty, and harmony were introduced into the material world. Such a matter was not absolutely without form, as is evident. Of the three opinions above mentioned about the nature of _materia prima_, the one maintained by Suarez is, in the present state of physical science, the most satisfactory, though it can scarcely be said to agree with the Aristotelic theory, as commonly understood. Indeed, if such a first matter is metaphysically constituted of act and potency, as he maintains, such a matter is nothing less than a primitive substance, as he also maintains; and we may be allowed to add, on the strength of the proofs given in our preceding articles, that such a first matter corresponds to our primitive unextended elements, which, though unknown to Suarez, are in fact the _first_ physical matter of which all natural substances are composed. But, if the first matter involves a metaphysical act and is a substance, such a matter cannot be the subject of _substantial_ generation; for what is already in act is not potential to the first act, and what has already a first being is not potential to the first being. Hence we may conclude that the first matter of Suarez excludes the theory of rigorously substantial generations, and leads to the conclusion that the generated substances are not new with respect to their substance, but only with regard to their compound essence, and that the forms by which they are constituted are indeed _essential_ to them, but not strictly _substantial_, as we intend hereafter to explain.