De metallorum ortu & causis

those subtle logicians should have established. However, one must grant some allowance for their ignorance. Furthermore, imperfecta metalla imperfect metals cannot yet be contained within their own genus until they attain the species and form of metal to which they are ultimately destined. For an embrio embryo in the womb of an animal is hardly called an animal until it has acquired the form of an animal. Again, some half-learned person might pointlessly object to us that certain metals are called imperfect by reason of their imperfectæ mistionis imperfect mixing or composition. This imperfection actually happens to all metals. Although they may be from the class of imperfectly mixed bodies, nevertheless each one exists as perfect in its own species because of the reasons already mentioned. Add to this that whatever has an essential form must necessarily be perfect. For the essential form, which is called ἐντελεχεία entelecheia; the condition in which a thing has reached its full development by the Greeks,