Cut eggplant into 1" cubes.  Sprinkle with the 2 teaspoons of salt and let stand in colander for approximately two hours.  Squeeze gently after the two hours to remove excess moisture. Saute eggplant in olive oil until brown on all sides.  Remove from pan with a slotted spoon.  Brown chopped onions until soft, add tomatoes, celery and olives, cook slowly until the celery is tender.  Return eggplant to the pan add capers.  Heat vinegar, stir in sugar until it is dissolved.  Pour mixture over eggplant mixture, add garlic, basil, salt and pepper.  Cover and simmer for 20 minutes, stirring occasionally.  Serve hot or cold.