4. In Him was life--essentially and originally, as the previous verses show to be the meaning. Thus He is the Living Word, or, as He is called in 1Jo 1:1, 2, "the Word of Life."
      the life . . . the light of men--All that in men which is true light--knowledge, integrity, intelligent, willing subjection to God, love to Him and to their fellow creatures, wisdom, purity, holy joy, rational happiness--all this "light of men" has its fountain in the essential original "life" of "the Word" (1Jo 1:5-7; Ps 36:9).

JFB.