Writing in the thirteenth century of our common era, Thomas Aquinas (1225-1274 CE) also explained the nexus between God’s self-disclosure and metaphorical vocalizations in the following way: “Now we are of the kind to reach the world of intelligence through the world of sense, since all knowledge takes its rise from sensation. Congenially, then, holy Scripture delivers spiritual things to us beneath metaphors, taken from bodily things.” While Aquinas believes that metaphors have their proper place in Christian discourse, he does not think that tropic speech is the only vehicle that believers can employ to reference or invoke God. Although Aquinas is intimately familiar with the vital role that metaphors play in Christian language and speech, he apparently chooses to predicate the term “Father” of God properly, not metaphorically (See ST 1.33.2). The basis for Aquinas’ non-metaphorical employment of the divine designation “Father” primarily lies in the distinction he makes between the thing signified (res significata) by a particular signifier and the human mode of signifying (modus significandi) itself.
Aquinas insists that the paternal nomenclature used of the putative first divine person in the triune Godhead hypostatically and eternally distinguishes him from the Son and holy spirit (ST 1.33.2). While Aquinas maintains that the Father, Son and holy spirit are all fully God, he still considers them distinct persons or subsisting divine relations. The respective eternal names and modes in which they putatively subsist are what differentiate the three persons (tres personae) one from another. Accordingly, Aquinas initially predicates paternity of God, then of creaturely essences, with respect to the entity signified (res significata) by the concept “father.” That is to say, Aquinas reckons that in the strictest sense of the word “father,” there is only one referent to whom the concept fittingly applies. That is, of course, God: “And call no [man] your father upon the earth: for one is your Father, which is in heaven” (Mt 23:9 KJV).
Human fathers, on the other hand, are authentic male parents (in the res significata sense) only to the extent that they partake theomorphically and analogically of God’s paternity. The “Angelic Doctor” (Angelicus Doctor) bases this argument on his reading of Eph 3:14-15: “I bend my knee to the Father of our Lord Jesus Christ from whom all paternity in heaven and on earth is named” (flecto genua mea ad Patrem Domini nostri Iesu Christi ex quo omnis paternitas in caelis et in terra nominatur). Nevertheless, he reasons that humans do not initially affirm that God is “father” in accord with the modus significandi sense. From this perspective, rational creatures first impute paternity to biological, forensic or sociological male figures before attributing it to God. Although Aquinas reckons that “Father” is a divine proper name (nomen proprium) with respect to the res significata sense, and thus not a metaphorical concept that rational creatures employ in the science of God-talk, he still recognizes the integral role that metaphors play in communicating divine verities.
 Nevertheless, he knows that Father is a “relational term” and not a name in the sense that YHWH or I AM are evidently nomina (ST 1.13.11). See Cooper, Our Father, 120. Aquinas, of course, employs the term “Father” in other ways as well.
 ST 1.33.2, Reply 4.
 See ST 1.33.3.