I write to you, fathers, because you know him who is from the beginning. I write to you, young men, because you have overcome the evil one. I write to you, little children, because you know the Father.
Thus one who sat down to write a letter to a friend might appropriately state in any part of the letter the reasons which had induced him to write at all to him on the subject. If he fixed his attention on the fact that he was actually writing, and on the reasons why he wrote, he would express himself in the present tense - I write; if on the previous purpose, or the reasons which induced him to write at all, he would use the past tense - “I have written” for such and such reasons. So John seems here, in order to make what he says emphatic, to refer to two states of his own mind: the one when he resolved to write, and the reasons which occurred to him then; and the other when he was actually writing, and the reasons which occurred to him then. The reasons are indeed substantially the same, but they are contemplated from different points of view, and that fact shows that what he did was done with deliberation, and from a deep sense of duty.