I've often been fascinated by this phenomenon --
For example, I used to think that a 40 year old is a Baby Boomer and/or someone who isn't very good with computers. In short, I firmly remember when my dad was 40.
Today, I am almost 40. My parents were Baby Boomers, and not even the oldest of them -- they were born in the 1950's, right in the middle of that generation. And I could have had computers growing up, though in point of fact my family couldn't afford one until I was 15. But I got right into computer programming. I've also been on the Internet since it was opened to the public.
Today, Baby Boomers are in their 60's and 70's.
When you reach 70 years old you regularly talk about time flying. First it is the years, then the months, then the weeks and now even the days go by like as a few hours. It is nothing now to miss a year or two when talking about a past incident.
Theories then come flooding out. Is time actually going faster these days? Is God fed up waiting to cause the next 'Flood' so He has hurried time? When my wife and others start brooding on these 'fast times' I say to them, 'well, at least we had them, unlike many others we know who died while young.
Then there is a witness to time that I undertook since I was a kid, me and a few pals. I was a constant initial carver, mostly on trees but a few times in cement. I can still witness my initial on a tree 1/3/49 (1949). I had another 1949 on a footpath but it was renewed recently. I put one on cement in my favourite swimming place a few years ago only to find recently it was 5/6/03, 13 years ago. I know there is another on top of a church that will never be seen again, only by God. When we were altar boys in 1952 and a new church was being built, one evening we climbed right to the very top, risking our lives (we didn't see it then like that) and carved out our initials on the lead covering, nearest to heaven we could get them.
Indeed I got the bug again in 2011 when I carved my initials on a young beech tree on 9/10/11, and again on 10/11/12. It will be another 100years before anyone can repeat that date on a tree.