first day of school

Why is it, after more than 20 years of teaching, that I still get anxiety before school starts? 
I love teaching. I love my students. I love what I teach. 
But I have nightmares (this year, at least, it wasn't the normal dream that my students had used the phone in the back of the room to order 100 pizzas, and, while I am trying to deal with the mix-up, they are jumping from desk-top to desk-top and I am wondering how the phone in the room, which only goes to the office, could have been used to order pizzas to be delivered!). Still, a night of nightmares over the weekend, and then two hours of sleeplessness in the middle of the night last night, wondering if I had thought everything through, if I had all the preparations REALLY completed. If I was ready. And what would I wear??? As if that mattered! 
Maybe it's because I know how important teaching (and teachers) can be. 
Maybe it's because I love what I do so much that I want it to be perfect (even though I know that's rarely possible). 
Maybe it's because I realize, more every year, how little control I have over what happens in my students' minds--that what they bring to the classroom is so vital to making a class "work" or not, and I have only so much influence on that. I can hope to establish a good sense of community, but I can't do it alone. Maybe it's that sense of what I want my classroom to be, every day and every year, and my own sense that such a classroom is a fragile and precious thing. And I don't want to mess it up for my students. 
What I do matters. But I'm not doing it alone. And that's what I remember every year at this time of year. And that's what brings the nightmares and the open eyes and wandering mind in the dark of the night when I should be asleep. 
But I wouldn't trade it for anything else I could do. 
Hooray for the first day!