From the Steve Miller Band: "Time keeps on slipping, slipping, slipping into the future." Except last Sunday. Then time slipped back an hour. Actually, time didn't slip, we just altered a mechanical measure of time.
Forgetting to turn your clock back, although changing nothing physically--the sun still rises in the morning and night still follows day--puts you completely out of synch in the human dance with time, showing up an hour early for appointments or recording the wrong TV shows.
One Fall Monday awhile ago, Byron and I showed up at the new 6 am Standard Time for our computer hotline job and began turning back the clocks. Julie walked over from the other side of the building and asked where everybody was. She'd been camping that weekend and hadn't had to deal with human time until now. It took awhile to convince her the time had changed. Nothing had changed for her and she couldn't trust practical jokers like me and Byron. It's easy to turn a clock to any time you wish. That's what we were doing when Julie "caught" us. She called time and temperature to get an independent opinion.
There is no absolute or individual measure of time. If we disagree on which coffee pot is closer to our boss's office, then Byron can get out a tape measure which has been calibrated against some international standard of length. Or I can pace off the distance to both pots myself, using a body-based measure. We can't do that with time. Although we have internal body clocks, they are notoriously unreliable when we are conscious. Seconds and hours can crawl by when you're waiting in the principal's office or lying in bed waiting for sleep, and time flies when you're having fun. And the external international standard second measured by a cesium clock translates randomly across time zones into seconds on our watches running on low batteries.
Physicists, for mathematical ease, have combined time with space into one four-dimensional space-time continuum on which they draw timelines circling a cone defined by light speed. These classic space-time graphs make it appear the entire trajectory of your life is sitting there, able to be comprehended as a whole. And generally, a self-history is perceived as a complete process leading to wherever you happen to be in life right now.
In one book, C. S. Lewis answers a question asked about a biblical passage which stated after death you will realize you've always been in heaven or hell. Lewis said it's because you will look back and realize each path you chose led to your current place. When I hit a low spot in life, I don't look back because I know every past choice will have been stupid, leading irrevocably to this putrid place. At those times, I try to plan ahead to create better times. Contemplation should only occur when life is good.
But in reality, it isn't life, it's attitude. Abe Lincoln said a man is as happy as he decides to be. If my entire life is a short line on the space-time graph, then I can't put an emotion on it any more than I can say a Cartesian parabola is happy. But I can choose to smile and hope others smile back. There's no point in dwelling in the past. I can't change anything. Even turning back the clock last Sunday doesn't turn back the clock of my consciousness, so I take conscious control of my attitude, something I can turn any direction I choose.