Either one, revelation or vision, may come without the other. There are three kinds of appearances:

1)Sensory or corporeal: The senses perceive a real object which is normally invisible. Need not be a real human body that is seen - may be a sensory or luminous form, or God or His agent may produce that image on the eyes of the one who sees the vision.

Note on Eucharistic visions: St. Thomas III. 76. 8 holds that Jesus does not appear in visible form in His real body since the Ascension. The appearances may come: (a) by His working on the exterior senses (usually when only one person sees the vision), so that there is nothing there in external reality. (b) There is something in external reality, but in the case of the Eucharist, there is a change in the figure, color etc. of the accidents of the Real Presence. (This is usual when more than one person sees or when the apparition continues and even is exhibited in a shrine). - St. Teresa of Avila, Relations XV (Peers edition I. pp. 341-42) seems to agree with St. Thomas: "From some of the things He said to me, I learned that, since ascending into the heavens, He had never come down to earth again to communicate Himself to anyone, except in the Most Holy Sacrament." - But others thinks there is a real presence, especially when He appears in proximity to the Sacred Host (cf. also the words cited above for St. Teresa, "except in the Most Holy Sacrament". When elsewhere, some think it is merely moral presence - others think there is a physical presence, and cite the case of St. Anthony kissing the Infant Jesus - a scene witnessed by the owner of the house where it happened: Cf. Poulain, Graces of Interior Prayer, pp. 315-16. On visions in general, cf. Poulain, pp. 301- 02, and Royo Marin, Teología de la Perfección Cristiana, pp. 815-19, A. Tanquerey, The Spiritual Life, pp. 701-02.

The same principles would apply to visions of the Blessed Virgin - and we note the varied images in which she appears.

2)Imaginative visions: produced in the imagination by God or angels or Saints, during sleep or when awake. Often an intellectual vision accompanies, which explains the meaning. -- These can be produced in three ways: (1)Awakening of images already present in memory, (2) Supernatural combination of such images held in memory, (3) Newly infused images. -- the devil can work in the first two ways , not in the third.

Such visions may come in sleep or while awake. May deal with things past or future as well as present. Cf. the case of the dreams of Joseph the patriarch. They may also be symbolic.

3)Intellectual visions: There is no sensory image present in these, the effect is directly supernatural on the intellect. There will be more clarity and force than what one would have from the natural powers. May come by way of ideas already acquired but coordinated or modified by God, or through infused ideas . The visions may be obscure , manifesting only the presence of the object, or they may be clear.

These intellectual visions may last a long time, days, weeks, even years. Cf. St. Teresa, Interior Castle 6. 8. 3. The effects may include profound understanding or love. They are apt to bring absolute certitude that they come from God: cf. St. Teresa, Life, 27. 5.

Combinations: In the Damascus road instance, Paul saw with his eyes a sensory vision, with his imagination he saw Ananias coming to him, in his mind he understood God's will.

Three kinds of revelations:

(Preliminary: distinguish public, found in Scripture and Tradition, completed when last Apostle died and NT was finished. Cf. Dei verbum § 4 - and private revelations: all else).

1)Auricular: A sound is produced in the air by a good or evil spirit. They may seem to come from a vision.

2)Imaginary: This does not mean false, but rather, a locution not perceived by the ears but by the power of image making. May be received while asleep or awake, and may come from God or a good or bad angel. By the fruits produced in the soul - if one examines all fruits, not just some -- one can see if the source is good or bad. Satan can afford to produce some seeming good fruits, if in the long run he can get evil results, such as disobedience to the Church over alleged visions, or pride, or may suggest great projects, beyond the ability of the soul, which will later give up all effort.

3)Intellectual: Impressed directly on the mind, with no images received in senses or imagination. There are three classes, according to St. John of the Cross - whom others follow (Ascent of Mt. Carmel II. 28-31): successive, formal, substantial.

1)Successive: These are formed by the soul, reasoning, with much facility, especially during meditation. They are the combined effect of the soul and the Holy Spirit. Illusion and error are quite possible here. St. John of Cross in II. 39. 4 says sometimes pure heresy can come in, created by the imagination of the soul or by the devil.

2)Formal: These seem to come from outside, whereas the successive seem to originate within the soul, even though the Holy Spirit may have a part in producing them. They, unlike the successive, may come even when one is distracted: thus the exterior origin is known. Illusion by the devil is possible here.

Substantial: Same as formal, but they produce in the soul the effects they signify, e.g. , if God says to the soul: be quiet, be humble. Royo Marin, op. cit, p. 821 , thinks no illusion is possible in such a case.

Note: 1)These locutions and visions belong to the category of gratiae gratis datae or charismatic, and per se are not necessary for spiritual growth of the soul, even though per accidens they may aid it. They do not even prove a soul is in the state of grace: cf. Mt 7. 22-23. But one should not desire these -- danger of self-deception or devilish deception. St. Teresa of Avila warns (Interior Castle 6. 9), cited above, warns of dangers.