For Thomas Aquinas, in a post-lapsarian economy, the Incarnation is the sole ground for the restoration of our participation in the divine understanding. Consequently, for us, not only are things true only as participating in God; also they are only true as conjoined to the body of the incarnate Logos. Aquinas therefore insists that, besides being sole bearer of grace to us, Christ is alone our reliable teacher, who restores for us also truth and knowledge.
To understand in what way he believes this to be the case, it is important to grasp how in general he conceives of the reasons for God becoming incarnate. For Aquinas, seemingly unlike Anselm, it is possible that God, according to his potentia absoluta, might have redeemed us, and re-instructed us in truth, without the incarnation of the Son. 1 A simple cancelling of our sins by decree, allied to an act of positive recreation, would in theory have been sufficient. By this assertion, he assures us that God had no need to be appeased in order to become reconciled to us, and that, in himself, he always and eternally was so reconciled. For Thomas, therefore, the Incarnation does not bring about this reconciliation of God, but rather mediates it to us, making it effective for us and in us, thereby ensuring that we, too, are reconciled.
However, this perspective might appear to entail that the economy of the incarnation of the Son was for Aquinas little more than an arbitrarily appointed means for our salvation. And, the consequence for a consideration of ‘truth’ would be that our restored intelligence possesses no essential, intrinsic relation to our indwelling the body of Christ, since God might have repaired the reality of our participation in his understanding (and our reflexive grasp of this) by some other means. Therefore, it would seem that while truth necessarily is participation in God, only accidentally and by appointment is it participation in Christ.
Such, however, is for Aquinas not at all the case. To comprehend why, one must briefly explore Aquinas’s view that while the actual means of incarnation and atonement adopted for our salvation were not absolutely