Many things once done cannot be undone!
Like good or bad; birth or death; love or war;
But thinking of yester-years- could be fun;
Whether you had cycled or gone by car.

Could we have done things better on that day?
Rewriting pages of golden history!
These kinds of thoughts bug me even today;
What man keeps doing is great mystery!

But often ’tis late to recast the past;
We move on to the future hopefully;
As time won’t wait and we ought to be fast,
Let humans take all things most gracefully!

Fretting, fuming o’er past is of no use;
’Tis Presently good ’cause I am a Muse!

Dr John Celes

http://www.poemhunter.com/poem/sonnet-forgetting-the-past/