For Descartes, would the following analogy hold?
res cogitans : res extensa :: ens rationis : ens reale
Or did Descartes distinguish the terms res cogitans from ens rationis and res extensa from ens reale?
ens reale = "real being" (a being in the natural world)
ens rationis = "being of reason" (which some consider a non ens or "non-being"); for an in-depth treatment of what entia rationis are, see John Poinsot (John of St. Thomas)'s Tractatus de Signis art. 1 ff.
res cogitans = "thinking thing"
res extensa = "extended thing"