Our Lord in St Luke’s gospel bids His disciples to be on the watch for His return using a phrase not found elsewhere:-
Blessed are those servants, whom the Lord when he cometh, shall find watching…If he shall come in the second watch, or come in the third watch, blessed are those servants.
If we apply these words to our death, then we might take the second and third watch to refer to the middle period of life, when death might seem more unlikely than at the beginning or the end (there were four watches in the night.) Cornelius a Lapide suggests that our Lord speaks only of those two watches because sleep is generally heavier at that time, and because He wishes to indicate that He will come when not generally expected.
But what if we apply the parable, as it can also surely be applied, not to individual deaths, but to Christ’s public return at the end of the world? What in that case might the second and the third watch mean? Someone could say that they have no special meaning, and simply add vividness to the parable. But if the fragments even of the miraculous bread were to be gathered up lest any be lost, how much more should the particles of the word of God be carefully preserved. So I am inclined to think that our Lord in mind some definite second and third watch of the future course of time.
One way of interpreting it is by the popular, though not unanimous, patristic idea of human history as a period of between six and seven thousand years, which I have summarised here. Of course this is contrary to the dominant current view in the natural sciences, but I leave this to one side, as such sciences have as their proper object the properties of natural things rather than past contingent events as such. Cornelius a Lapide considered it likely that human history would last six complete millennia and then an uncertain portion of the seventh millennium. This would correspond to the account of creation in Genesis, where the first six days are said to come to an end, but no evening is mentioned for the seventh day. On his calculations, Adam was created in 3950 BC. Adding six thousand to this, one reaches AD 2050, which would complete the six millennia. Lapide therefore considers that the world will come to an end some time between 2050 and 3050.
We could divide this seventh millennium into four quarters, or watches, of 250 years each. The second and third quarters would therefore run from AD 2300 to 2800. So perhaps our Lord is giving us a hint that His return will take place at some time in that period.
Of course, I could be quite wrong. But the question would still remain: what is the second watch? What is the third?