Butternut Squash Soup II

INGREDIENTS

• 2 tablespoons butter
• 1 small onion, chopped
• 1 stalk celery, chopped
• 1 medium carrot, chopped
• 2 medium potatoes, cubed
• 1 medium butternut squash - peeled, seeded, and cubed
• 1 (32 fluid ounce) container chicken stock
• salt and freshly ground black pepper to taste