Etymologically, species (in-spicere) is what eidos (idein) is in Greek. Species is scholastic Latin for eidos. Now eidos meant one thing in Plato, and another in Aristotle. Species labours under a similar ambiguity. In the objection now under consideration, the words of which are esse perpetuum speciei dicitur divinum esse, the language is rather Platonic than Aristotelian. Individual men, John, Peter, Martin, pass away: but the species, or idea, of 'man' is perpetual and divine, an abiding type of possible creation, founded upon the divine essence and known in the divine understanding eternally. These archetypical ideas, -- intelligibilia St Thomas calls them, -- have been discussed already (B.I, Chapp. LI [LII, LIII] - LIV). The following account of them will commend itself to all Christian lovers of Plato.
"God contains in Himself in exuberant fulness that delights or can give pleasure. All the perfection that is divided among creatures, is found united in Him; and He is all things, He is the uncreated being of all things, inasmuch as He is the archetype and exemplar of them all. He had in His eternal knowledge the divine plans and ideas of the things that He made; and whatever was created by Him was for ever known by Him, has always lived in His mind, and always shall live there. Hence the Gospel says: What was made, in Him was life (John i, 3, 4, as read by many of the Fathers). Hence we too from eternity have had an ideal existence in God: in Him I say, we have been and are uncreated, in whom, or in whose knowledge, all things eternally live and are life. In the essence of God therefore there are exemplars of all things; and the same divine essence is the one exemplar and the one idea of all. For all the multiplicity of creatures is reduced to unity in the sheer, simple, and superessential essence of God; and all things in God are one. There are therefore in God most true and perfect exemplars of things, which remain incorrupt for ever: whereas the things that we see in this sensible world are mere symbols and signs of reality, that pass away with time and perish" (Blosius, i.e. Louis of Blois, O.S.B., Institutio Spiritualis, Opera Omnia, Cologne, 1571, p. 423).
Of God and His Creatures: 2.32