"Thomas says again and again that everything proceeds from [the First Person], and that to [the First Person] everything returns; that the entire Trinity is present as much in the creation as in the inhabitation; but [that] the 'less direct and more secret' presence of the Father seems to be attainable only through his intermediaries, his Word and his Spirit (Émile Bailleux, La création, oeuvre de la Trinité selon saint Thomas (1962), p. 48-49).
"Thomas never speaks, as he did for the Son and the Spirit, of an experimental perception of the presence of the Father. He says, rather, that the Father himself se liberaliter communicat creaturae ad fruendum [(communicates himself liberally for the enjoyment of the creature)] (Ia q.43 a.4 ad 1), and draws upon Augustine in order to assure [us] that [the Father] is known by us in the same manner as the Son and the Spirit. From this one can therefore legitimately conclude that if he 'gives himself', this is in order to be 'possessed'. Yet one cannot identify a gift appropriated [to the Father]—to match the [gift of] wisdom [appropriated] to [(pour)] the Son or the [gift of] love [appropriated] to [(pour)] the Spirit—from which that experimental knowledge [of the Father] would be derived, and one falls back on 'a sort of conjoint perception of the Father with the Son or with the Spirit' (Albert Patfoort, "Missions divines et expérience des personnes divines selon saint Thomas," Angelicum 63 (1986): 552n15)."
Jean-Pierre Torrell, “Thomas d’Aquin,” Dictionnaire de spiritualité 15 (1991), col. 755 (718-773).