In a large stock pot, cover peas with 2 quarts cold water and soak overnight. If you need a faster method, simmer the peas gently for 2 minutes, and then soak for l hour.
Once peas are soaked, add ham bone, onion, salt, pepper and marjoram. Cover, bring to boil and then simmer for 1 1/2 hours, stirring occasionally.
Remove bone; cut off meat, dice and return meat to soup. Add celery, carrots and potatoes. Cook slowly, uncovered for 30 to 40 minutes, or until vegetables are tender.
