“When it is written that the Apostles Peter, Andrew, John and James gathered together to ask for the cure of Simon’s mother-in-law, this is a very important matter. For this request represents the Communion of Saints, by which the body of the Church is so united that all its members share in the good of one another. From this it follows that all Christians share in all the prayers and good works which are offered in Holy Mother Church. This communion exists not only here below on earth, but in Heaven as well. That position is foolish and stupid, then, which, though willing to believe in the Communion of Saints on earth, will not believe that it extends to Heaven. Certainly, people who hold that view do not believe in that article of the Apostles’ Creed. It is most certain that, as we share here below in the prayers of one another, so these same prayers and good works profit the souls in Purgatory, who can be helped by them. Moreover, they and we share in the prayers of the blessed, who are in Paradise. It is in this that this Communion of the Saints consists. This article of faith is symbolized by the cure of our sick woman, who was not relieved by her own prayers, but by those of the Apostles, who interceded for her.”
–St. Francis de Sales, Sermon for the Thursday of the third week in Lent, 1622.