Jamieson, Fausset and Brown on John 1:5

5. shineth in darkness, &c.--in this dark, fallen world, or in mankind "sitting in darkness and the shadow of death," with no ability to find the way either of truth or of holiness. In this thick darkness, and consequent intellectual and moral obliquity, "the light of the Word" shineth--by all the rays whether of natural or revealed teaching which men (apart from the Incarnation of the Word) are favored with.

the darkness comprehended it not--did not take it in, a brief summary of the effect of all the strivings of this unincarnate Word throughout this wide world from the beginning, and a hint of the necessity of His putting on flesh, if any recovery of men was to be effected (1Co 1:21).