In a 4- or 5-quart pot, combine the broth, celery, carrots, onion, bay leaf, parsley and thyme. Bring to a simmer and cook, covered, until the vegetables are tender, 8-10 minutes. Stir in the noodles and cook according to package directions until al dente. Add the chicken and cook for another 1-2 minutes. Season to taste with salt and pepper (important!) and serve.