"this lamp of law and faith"

     "Consequently, that brilliant lamp which was lit for the sake of our salvation should always shine in us.  For we have the lamp of the heavenly commandment and spiritual grace [(lucernam caelestis mandati et gratiae spiritalis)], to which David referred:  Your law [(mandatum)] is a lamp to my feet and a light to my path.  Solomon also says this about it:  For the command of the law [(praeceptum legis)] is a lamp. . . .
     "Therefore, we must not hide this lamp of law and faith [(lucerna haec legis ac fidei)].  Rather, we must set it up in the Church, as on a lamp-stand, for the salvation of many. . . ."

     St. Chromatius, Tractate 19.4.1 and 3 on Matthew 5:14-16, as trans. Office of Readings for the Feast of St. Barnabas (11 June), Liturgy of the hours.  =CCL 9, 287 ll. 66 ff., as reproduced in the 2014 Breviario Digitale edition of Liturgia horarum, except with haec for hic, as in the IBreviary (I have not yet checked CCL 9, but lucerna is, of course, feminine).  ACW 75 trans. Schenk, p. 191:

And, therefore, this spiritual lamp that was set alight for the benefit of our salvation should always shine in us.  For we have the lamp of the heavenly commandment and of spiritual grace of which David has spoken:  'Your commandment is a lamp to my feet and a light to my paths' [Ps 119:105].  And Solomon says of it, 'For the precept of the law is a lamp' [Prov 6:23]. . . .  Whence we must not conceal this lamp of the law and of faith, but it should always be set in the church as on the lampstand for the salvation of many. . . .