New England Clam Chowder

1-1/2 sticks butter
1 cup onions, diced
1 cup celery, diced
1/2 cup all-purpose flour
4 cups hot milk
3 cups clam juice
4 3-1/2 oz. cans clams
1/4 tsp. white pepper
1/4 tsp. dried thyme
Salt to taste
1 cup potatoes, diced

Heat butter in a large stockpot and saute' onions and celery until clear. Add flour, cook and stir with a whisk for about 10 minutes. Gradually add hot milk, stirring with whisk until smooth and thickened. Add clam juice, stir and simmer for 15 minutes. Add clams, white pepper, thyme, salt and potatoes. Bring to a boil, then reduce heat and simmer for 15 minutes. Serve with crackers or a good crusty bread.