Mercy and Enlightenment

Post misericordiam enim et benedictionem id sequitur: Illuminet vultum suum super nos, et miseratur nobis. Benedictione Dei opus est, ut nos vultus ejus illuminet ut tenebrosa corda nostra cognitionis suae lumen irradiet, ut majestatis suae Spiritus lucem obscuratis intelligentiae nostrae sensibus tribuat; et gloriari deinceps liceat, dicentes: Designatum est super nos lumen vultus tui Domine. Hanc autem illuminationem vultus sui super nos misericordia ipsius, quae in peccati remissione in nobis est coepta, largitur. In quem autem profectum illuminationem vultus Dei super se precentur, sermo consequens docet: Ut cognoscamus in terra viam tuam, in omnibus gentibus salutare tuum. Sanctus Hilarius Pictaviensis,Tractatus super Psalmos, Tractatus in Psalmum LXVIII

And after mercy and blessing it follows: Let the light of your face shine upon us and be merciful to us. 1 In the blessing of God is the work that his face shine upon us and enlighten with the light of His knowledge our dark hearts, that he give to the darkened understanding of our minds the light of his majestic spirit, that then we be able to glory, saying, Sealed upon us is the light of your face, O Lord. 2 This light of His face upon us is His mercy poured forth, which undertakes the forgiveness of sin among us. And that they pray for this coming illumination of the face of God upon them, the next verse teaches, saying: 'That we might know on earth your way, among all the peoples your salvation.' 3 Saint Hilary of Poitiers, Homilies on the Psalms, Psalm 66  1 Ps 66.1 2 Ps 4.7 3 Ps 66.3