 That is, on this framing, to be actual is to be either concrete or necessarily non-concrete; or, more simply put, it is to be either concrete or abstract. It is a straightforward exercise to show that, under this definition of actuality, \(\textbf{Poss}_{\sfC}\) is equivalent to the original definition  Poss  and that \(\textbf{Act}_{\sfC}\) is equivalent to the principle  \(\textbf{Act}^{*}\)  that, necessarily, everything is  actual.[28]