Such is the question pursued by Martignani in this extensive analysis of the thirty-one occurrences of the term in John. He concludes that such a common measurable extent of time can, in fact, possess extensive theological and Christological meanings, not all of which are of equal value. Each of these three is made the subject of wide-ranging examination. There exists in John a concatenation of symbols.
Day is the time of light, which is thus opposed to the time of darkness which represents unbelief.
Even when a simple chronological indication is the primary meaning in a given text, this additional symbolic value is lurking in the background. The first, second, and fourth of the above examples contain a strong reference to Easter. This day has been prepared for by his death on the cross, which is really his glorification, his being lifted up to the Father. These are not later insertions meant to counter a Johannine insistence on realized eschatology, but the natural and inevitable complement to the work of Jesus that remains unfinished if limited to this aeon alone. Judgment and resurrection are the events to be awaited on the last day, events presaged by the communication of Jesus himself through his Word and the Eucharist.