Why do you have to be so grown up?

My son is not even 2 and he has to do things all grown up. He doesn't want me to hold his hand as he goes down the stairs, or even help him get his coat off anymore. Our screen door doesn't latch in our new home, so if the big door is open, he can open the screen and leave if he wants. Praise God he hasn't yet, but the thought that he's capable of doing it makes me so sad. Today, I was bringing in groceries and this little 20 month old opens the door for me. Who is this tiny (well, he was never a tiny newborn) little man that used to be my baby? He talks on the phone, "Yeah... hmmm, oh, okay... sure... bye!" its so grown-up!
He's going to wake up on Monday assuming all is normal. Then he will lay down for his nap, wake up and find out that he's a big brother. A BIG brother! No! he can't be! He's a baby! But no matter what I do, he keeps getting older and more "grown-up". And I hear this will not stop! Soon I will have another little tiny baby. And she might grow up too! What will I do?
I adore the new things he can accomplish, and even though its a pain that he can get out of his room so early in the morning, its nice to know we've taught him some independence... Its just that he could have waited a bit longer to grow up!
Dave's favorite thing now is how Zech will get up ever so quietly, open his door without a creek, and sneak into our room in the early morning. He walks up to Dave's side of the bed and gently brushes his cheek. Dave purposely rolls over about 5:30 am just so he's ready for the wonderful awakening! But I remember when I'd hear this tiny baby coo in his bed in the mornings, and I'd go in and peek into his crib and he'd look up at me and kick his feet, flail his arms around, and squeal in delight as I'd scoop him up and cuddle him in my arms. No baby bed for him. No sitting still so Mommy can come in and scoop him up. Its running and jumping and climbing stairs without Mommy now!
But he's still just as cute, and oh so intelligent! I marvel at all he can learn in one day. And how cute it is to hear him say "More Melk Pees!" or "Um, yeah, okay, mama!" in response to my questions. I guess its not a complete disaster for him to grow up... I just can't believe how quickly it happens!!!