Meaning
In 2Co 3:18, for katoptrizomenoi, the English Revised Version gives "reflecting (as a mirror) the glory of the Lord," the American Standard Revised Version "beholding (as in mirror," etc.). Katoptron was a mirror of polished metal. We cannot clearly and fully behold the outshining of spiritual grandeur in Christ Jesus, but in the gospel God accommodates and adjusts the vision as we are able to bear it, and the glory beheld becomes glory imparted to (and reflected by) the beholder.
John's Gospel gives us theaomai ("to look closely at"), and theoreo ("to discern"). "We beheld (etheasametha) his glory" (Joh 1:14), "that they may behold (theorosin) my glory" (Joh 17:24). In classic literature, the former word is closely associated with theatrical spectacles, and the latter with athletic games, and they both convey the idea of unceasing interest, deepening in this connection into love and joy.
M. O. Evans