New Thoughts
The connection to the remainder of the letter seems a little clearer now; that he explains his reasons for writing and the reasons why his readers ought to give it their attention. As to the issue of ages here - I still tend to hold to the three ages view. If the address to the youngest seems to fit all, it is simply because none progress to adulthood without having been born a child. Thus what is true of the child, has been true for all - and in this case remains true for all. In contrast, the characteristics of the young man are unique to that group, and are a past memory to the elder. The strength of the elders lies in a different place - not in their victorious power in battle, but in their abiding peace and their breadth of knowledge in the things of God. Each of these retains the forgiveness which constitutes their birth. Each will progress to, be, or have progressed to strong service in God's purposes - given attention to His commandments. One can see the addresses to younger ages serving to remind the older ages of their foundations, and the addresses to the older acting as incentives to the growth of the younger in faith and service. Are these declarations of the ages of growth in love? Yes. At the same time, they are reminders to those at the various stages of what has been and what is to come in their spiritual life. They are - as Matthew Henry points out - reasons to let go the world, and to break its hold upon us, whatever the stage of our Christian walk.