SPIRITUAL COMMUNION. - I. A eucharistic practice consisting, as the Council of Trent says (sess. XIII, c. 8: Denz-U, n. 881), in the votum Sacramenti: it is a uniting oneself to Jesus Christ present in the Eucharist, not by receiving him sacramentally, but through a lively desire proceeding from faith animated by charity. In the supernatural order, desire can sometimes take the place of certain sacraments (when it is impossible to receive them), to the point of causing justification, as does the desire, at least implicit in an act of charity or contrition, for Baptism and Confession. Thus the desire for sacramental Communion has an efficacy that approaches that of the Sacrament.
Spiritual Communion is made up of three acts: 1) faith in the real presence of Jesus Christ in the Eucharist; 2) the desire (which here must be explicit) for sacramental Communion; 3) thanksgiving for the gift that Jesus makes of himself, as in sacramental Communion. It may be repeated as often as one wishes: but it is particularly recommended at Mass, at the priest's Communion; the Council of Trent, in giving this counsel, draws from it the proof that all Masses, even those at which only the priest communicates, are the sacrifice offered by the faithful, because they communicate spiritually (sess. XXII, c. 6: Denz-U, n. 944).
For spiritual Communion, Confession is not required: should the faithful be in sin, he must precede the act of contrition to the desire to communicate, otherwise he would lack an essential disposition, namely charity; but he is not obliged to precede it with Confession as for sacramental Communion.
The effects of spiritual Communion, moreover, are identical to those of sacramental Communion, that is, an increase of grace and of virtuous habits, in other words spiritual nourishment; but they are certainly less intense, since they are not produced ex opere operato (that is, by virtue of divine institution), but only ex opere operantis (that is, by virtue of the individual's dispositions, and are proportioned to these). St. Thomas says: «Sacramentalia manducatio plenus inducit Sacramento effectum» (Sum. Theol., 3ᵃ, q. 80, a. 1, ad 1). They are always, however, very precious effects, among which is that of immensely reviving faith and love for the Most Holy Sacrament and of impelling one toward sacramental Communion.
II. In a wholly different sense, the name of spiritual Communion is given to a particular mode of prayer, taught by the venerable Olier and promoted by him in the seminary of St. Sulpice in Paris (Catéchisme chrétien pour la vie intérieure, lesson 8). According to Olier, the process of prayer, besides the preparation and the final colloquy, consists of three distinct acts, which must always be performed, whatever passage of the life of Christ one is meditating on, namely adoration, communion and cooperation. After adoration (thinking with faith and love of Jesus present in that given point), communion (or rather communication) consists in applying to oneself the teaching of Jesus, striving to conform oneself to him in one's ideas and in one's affections. It is followed by cooperation, made up of practical resolutions according to the light received, in order to order one's life holily. It is a method of meditation in which attention is paid rather to the effects than to the development of the matter; and spiritual Communion is a psychological and moral conformation, not a desire for sacramental union.