[20] Gilbert de la Porrée in his commentary on the De Trin. makes Boethius's meaning clear. "Quod igitur in illo substantiam nominamus, non est subiectionis ratione quod dicitur, sed ultra omnem quae accidentibus est subiecta substantiam est essentia, absque omnibus quae possunt accidere solitaria omnino." (Migne, P.L. lxiv. 1283). Cf. Aug. De Trin. vii. 10.
[21] i.e. according to their substance.
[22] The doctrine is Augustine's, cf. De Ciu. Dei, xi. 6, xii. 16; but Boethius's use of sempiternitas, as well as his word-building, seem to be peculiar to himself. Claudianus Mamertus, speaking of applying the categories to God, uses sempiternitas as Boethius uses aeternitas. Cf. De Statu Animae i. 19. Apuleius seems to use both terms interchangeably, e.g. Asclep. 29-31. On Boethius's distinction between time and eternity see Cons. v. pr. 6, and Rand, i er dem B. zugeschr. Trakt. de fide, pp. 425 ff, and Brandt in Theol. Littzg., 1902, p. 147.
V.
Age nunc de relatiuis speculemur pro quibus omne quod dictum est sumpsimus ad disputationem; maxime enim haec non uidentur secundum se facere praedicationem quae perspicue ex alieno aduentu constare perspiciuntur. Age enim, quoniam dominus ac seruus relatiua sunt, uideamus utrumne ita sit ut secundum se sit praedicatio an minime. Atqui si auferas seruum, abstuleris et dominum; at non etiam si auferas albedinem, abstuleris quoque album, sed interest, quod albedo accidit albo, qua sublata perit nimirum album. At in domino, si seruum auferas, perit uocabulum quo dominus uocabatur; sed non accidit seruus domino ut albedo albo, sed potestas quaedam qua seruus coercetur. Quae quoniam sublato deperit seruo, constat non eam per se domino accidere sed per seruorum quodam modo extrinsecus accessum.
Non igitur dici potest praedicationem relatiuam quidquam rei de qua dicitur secundum se uel addere uel minuere uel mutare. Quae tota non in eo quod est esse consistit, sed in eo quod est in comparatione aliquo modo se habere, nec semper ad aliud sed aliquotiens ad idem. Age enim stet quisquam. Ei igitur si accedam dexter, erit ille sinister ad me comparatus, non quod ille ipse sinister sit, sed quod ego dexter accesserim. Rursus ego sinister accedo, item ille fit dexter, non quod ita sit per se dexter uelut albus ac longus, sed quod me accedente fit dexter atque id quod est a me et ex me est minime uero ex sese.
Quare quae secundum rei alicuius in eo quod ipsa est proprietatem non faciunt praedicationem, nihil alternare uel mutare queunt nullamque omnino uariare essentiam. Quocirca si pater ac filius ad aliquid dicuntur nihilque aliud ut dictum est differunt nisi sola relatione, relatio uero non praedicatur ad id de quo praedicatur quasi ipsa sit et secundum rem de qua dicitur, non faciet alteritatem rerum de qua dicitur, sed, si dici potest, quo quidem modo id quod uix intellegi potuit interpretatum est, personarum. Omnino enim magna regulae est ueritas in rebus incorporalibus distantias effici differentiis non locis. Neque accessisse dici potest aliquid deo, ut pater fieret; non enim coepit esse umquam pater eo quod substantialis quidem ei est productio filii, relatiua uero praedicatio patris. Ac si meminimus omnium in prioribus de deo sententiarum, ita cogitemus processisse quidem ex deo patre filium deum et ex utrisque spiritum sanctum; hos, quoniam incorporales sint, minime locis distare. Quoniam uero pater deus et filius deus et spiritus sanctus deus, deus uero nullas habet differentias quibus differat ab deo, a nullo eorum differt. Differentiae uero ubi absunt, abest pluralitas; ubi abest pluralitas, adest unitas. Nihil autem aliud gigni potuit ex deo nisi deus; et in rebus numerabilibus repetitio unitatum non facit modis omnibus pluralitatem. Trium igitur idonee constituta est unitas.
V.
Let us now consider the category of relation, to which all the foregoing remarks have been preliminary; for qualities which obviously arise from the association of another term do not appear to predicate anything concerning the substance of a subject. For instance, master and slave[23] are relative terms; let us see whether either of them are predicates of substance. If you suppress the term slave,[24] you simultaneously suppress the term master. On the other hand, though you suppress the term whiteness, you do not suppress some white thing,[25] though, of course, if the particular whiteness inhere as an accident in the thing, the thing disappears as soon as you suppress the accidental quality whiteness. But in the case of master, if you suppress the term slave, the term master disappears. But slave is not an accidental quality of master, as whiteness is of a white thing; it denotes the power which the master has over the slave. Now since the power goes when the slave is removed, it is plain that power is no accident to the substance of master, but is an adventitious augmentation arising from the possession of slaves.
It cannot therefore be affirmed that a category of relation increases, decreases, or alters in any way the substance of the thing to which it is applied. The category of relation, then, has nothing to do with the essence of the subject; it simply denotes a condition of relativity, and that not necessarily to something else, but sometimes to the subject itself. For suppose a man standing. If I go up to him on my right and stand beside him, he will be left, in relation to me, not because he is left in himself, but because I have come up to him on my right. Again, if I come up to him on my left, he becomes right in relation to me, not because he is right in himself, as he may be white or long, but because he is right in virtue of my approach. What he is depends entirely on me, and not in the least on the essence of his being.