Where has my baby gone?

Bug will be four in less than a week.
I'm having a tough time with it.
I keep looking at this tall, quick boy and expecting to see the crying, squishy baby I held not so long ago.
I listen to him announce his intentions, his likes and dislikes, and tell me about his day, and remember when I was so ready for him to talk. Now I can't get him to not talk. About everything.
I look at those size ten feet and remember the feel of his mutant monkey toes lodged in my ribcage as he performed prenatal acrobatics in my womb.
When he reaches for my hand, I remember the feel of those wrinkled baby soft fingers curling around my finger for the first time.
Four years is an eternity to Bug. It's been a time of growth, development, and discovery. He's gone from a newborn to a boy in a heartbeat, or so it seems to me.
I always hated being told that I was growing up too fast, that I should slow down.
Now, as a parent, I find myself thinking these same thoughts.
Four years is a second to me looking back.
Four years is a blink of an eye in the life of a child.