Mash or rice the potatoes, put them in a large bowl. Melt the butter in a skillet, pour most of it over the potatoes. Saute' the celery and onion until the celery is tender. When done add this to the potato mixture. Add the sage, salt, pepper and parsley. Blend well. Either stuff a goose, turkey or chicken with this and roast in the oven according to the time needed per the weight of your poultry. OR Bake in the oven in roast pan at 350 degrees for 20 minutes.