I believe the answer to your poem is time. See below. ;-)
The time has come,
winter is here
and those yellow bears disapear.
The time has past
as man looks back with a sigh
and a tear in his eye.
As time is held
boys cross their legs
but of course the toilet begs
As time marches on
Girls loose their blush
and swap a comb for their brush
As time passes
For those held high
their end is nigh
As time catches up
Everyone is equal
when we get to the final sequal
As time turns
Without it we have flour and water
With it we have breakfast for my daughter
As time revolves
How does one turn water and wine
into something so fine
As time runs out
The more in a minute you try and squeeze
the less you can do with ease.
As time ticks
All the time that has past
man cannot comprehand something so vast.