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cf., ST.I.Q44.A3; Sent.I.D36.Q2.A1; QDeVer.Q3.A1; Metaph.Bk1.L15
In the previous question, St. Thomas was concerned with the extension (and manner) of the Divine Knowledge. Here, he is more specifically concerned with practical knowledge, which treats of the exemplars and their relation to created things that he effects (cf., quotation in introduction by Poinsot).
St. Thomas begins this article by clarifying that by "idea," we mean the form of thing apart from the thing. For those confused by the language of "form," in it we seek to designate the active principle in a certain thing that places it within its species, in contrast to matter which is the potential principle of a certain thing that individuates it.