Where Has the Time Gone?

Munchkin #2 will be turning 4 on the 20th and today we brought home his birthday present...a bona fide Big Boy Bike! Where has the time gone? It seems like just yesterday we were bringing home a bike for our eldest and now we're pecking right on down the line. I know they can't stay young forever, and 4 is by no means "old", but it's all happening a bit too fast for Mommy. For all the chaos having 4 young children brings, I'm in no hurry to see them grow up and into a period of relative calm. They change so much each day and are so engaging...I'm just not ready to face the fact that one day, they won't want to tell me every little detail of their days and may, in fact, request that I (heaven forbid) give them space! Oh the horror!