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.

 We do not say that there is no thought of age groups in this. There almost certainly is; but John has a way of saying things which can be taken in two ways, a narrower and a wider; and, while the narrower meaning is here, we must go beyond it to find the full meaning. 