It’s always easier to speak from experience, in which case the best reply to this question would come from Doctors of the Church Hildegard of Bingen (recently named) and Catherine of Siena as well as other saints like Francis of Assisi, Bernadette of Lourdes, or any number of folks on the biblical record like Jacob, Isaiah, Ezekiel, Peter, Paul, and John of Patmos, who wrote the Book of Revelation.

ICON of Hildegard of Bingen

From me, you can get a definition. Visions are understood to be the product of God’s self-communication. As Carmelite Father John Welch puts it, all of Christianity depends on divine revelation, so the hop to visions is not all that unusual for people of faith. Nonetheless it is an extraordinary event that can be expressed in words, ideas, or images. It may have a physical dimension but is more often experienced in the imagination or intuitive understanding.

Visions that include a tangible dimension are considered extremely rare. Juan Diego got an image on tilma cloak from Our Lady of Guadalupe. Philip Neri experienced a globe of fire entering his chest that literally broke his ribs and enlarged his heart. Francis of Assisi had his stigmata. Most visions don’t have that kind of corporeal aspect, and mystics themselves often mistrusted them if they did. “Imaginative visions”—Joan of Arc described hers this way—are often attributed to factors like youth, an elementary religious education, or psychological simplicity. Consider how many mystics had their experiences as children, like those of the Virgin Mary at Fatima, Portugal in 1917.

Mystics agree the most reliable visions are intellectual or intuitive; these are less likely to be distorted by unreliable human senses. Mystics are also the first to say that visions are not the goal of the spiritual life. Most mystics had their visions early and moved into a greater interiority of spiritual communion with God after that. In that sense the vision achieved its purpose along the spiritual journey as a boost upward into something richer and more useful—the point being, for the saints and for the rest of us, that we shouldn’t measure ourselves against these experiences or hanker after them. If even visionaries found them dispensable, they are clearly not prerequisites to grace.

Although faith is based on revelation, church teaching leaves the matter of specific visions open to question. Visionaries in modern times are subject to investigation by church authorities and may be deemed credible—but their experiences are not made matters for doctrinal acceptance for believers. Most of us have inexplicable episodes when we perceive things we have no way of knowing and yet do. If we pay attention, we might see more than we think.

Scripture
• Genesis 32:23-33; Isaiah 6:1-8; Ezekiel 10; Daniel 7:13-18; Acts of the Apostles 9:1-9; 10:9-16; the Book of Revelation

Online
• The Dialogue of Saint Catherine of Siena, "dictated by her, while in a state of ecstasy, to her secretaries, and completed in the year of our lord 1370"

Books
• Our Lady of the Lost and Found: A Novel of Mary, Faith, and Friendship by Diane Schoemperlen (Penguin, 2002)
• Mystics and Miracles: True Stories of Lives Touched by God by Bert Ghezzi (Loyola Press, 2002)

In this question we put two dogmas together: belief in the Blessed Virgin Mary’s Assumption and in the virgin birth of Jesus. We might add the Immaculate Conception of Mary, because a discussion of one of these touches on them all. Theologian Sister Elizabeth Johnson, C.S.J. calls these dogmas “prophecy in the midst of the history of suffering.” Prophetic statements are matters of faith and not available for scientific validation.

Nor do these dogmas necessarily spring from the record of scripture. Chapter-and-verse proof-texts for the Assumption and the Immaculate Conception in particular are unsatisfying because neither event is covered in the New Testament. The Assumption was formally declared (“promulgated”) as dogma in 1950 by Pope Pius XII, but that doesn’t mean the church has only recently taught it.

The early church fathers don’t address the matter of Mary’s departure from this world, but possibly as early as the 3rd century the tradition of Mary’s “transitus” recounted her bodily reception into heaven. Roman Catholics, Eastern Orthodox, and even some Anglicans hold some version of the Assumption in their traditions; Roman Catholicism does not define whether Mary “fell asleep” or “died” before her body was taken up.

The theological argument for the Assumption is one of “fittingness.” Mary is the Ark of God’s new covenant in Christ. She was preserved from sin for this end (her Immaculate Conception) and should not undergo the corruption of death (see Romans 6:23 on the wages of sin). Her body, given over to God’s purposes in the divine plan of salvation, became a vessel too sacred to be discarded or forgotten afterwards. Scholastic thinkers like Aquinas and Bonaventure used the Latin phrase “potuit, voluit, fecit” to sum up the idea: God “could do it, willed it, and did it.”

Perhaps a more humanly compelling argument arose in the wake of the 20th century’s two brutal world wars. Pius XII surveyed the ghastly indignities suffered by the human body in recent memory and saw an opportunity to teach emphatically that God cares what happens to our mortal flesh. Mary’s exalted destiny may bring “clearly to the notice of all persons” the destiny of our bodies and souls. You and I are also vessels of divine life too precious to God to forget.

Scripture
• Genesis 3:15; Luke 1:41-45; 1 Corinthians 15:21-26, 53-57; Revelation 12:1-17

Online
• Apostolic Constitution of Pope Pius XII, Munificentissimus Deus, Defining the Dogma of the Assumption

Books
• Truly Our Sister: A Theology of Mary in the Communion of Saints by Elizabeth A. Johnson (Continuum, 2003)
• Mary: A History of Doctrine and Devotion by Hilda Graef and Thomas A. Thompson (Christian Classics, 2009)
• Mary: Images of the Mother of Jesus in Jewish and Christian Perspective by Jaroslav Pelikan, David Flusser, and Justin Lang (Fortress Press, 2005).
• Mary Through the Centuries: Her Place in the History of Culture by Jaroslav Pelikan (Yale University Press, 1996)
• Mother of God: A History of the Virgin Mary by Miri Rubin (Yale University Press, 2010)

The rosary is a method of prayer, not a mandate. It doesn’t hold the weight of a precept of the church, like the one that obliges Catholics to gather for Mass each Sunday. Like the Stations of the Cross, Adoration of the Blessed Sacrament, or daily scripture reading, I think of it as an offering of the church: a way to grow closer to God and the divine mysteries.

So what’s to be gained by this particular prayer form? The rosary supplies a healthy appreciation of Mary’s role in Catholic identity: the whole-souled human response to God's invitation that she embodies so beautifully. Mary is the realization of our vocation to “be church.” She is what we must become. Mary shows us how discipleship is done. But she’s not to be confused with a celestial celebrity. She's better than that. She's the one who assures us that saying yes to God, fully and completely, is possible. Her story and her destiny shine a light on human potential in relationship to God. We, too, yearn to become “full of grace.”

The rosary offers a unique view of the gospels through the heart of the woman from Nazareth. Mary was the first to ponder the greatest events of salvation history. Through her eyes, we reflect on these moments of joy, light, sorrow, and glory and learn to appreciate life’s sacred dimensions. Birth and death, joy and grief, expectation and loss are not only details of our humanity but mysteries connected to sin and grace. We reclaim all the hours of our experience as holy when we pass these simple beads through our hands.

The rosary multiplies the avenues of prayer. It's Scripture meditation, petition, song of praise, and instruction in the faith all at once. Pope Pius XII called it a "compendium of the entire gospel" presented in jewel-like cameos. Blessed John Henry Newman declared that the rosary provides us with a way of "holding in our hands all that we believe." Silence and vocal prayer are the rosary’s alternating energies. If we race through it, we miss the graced encounter that lurks between the beads. Pope John Paul II declared that a "rosary personality" is a witness against violence, injustice, arrogance, and intolerance in any form. In which case we might hope more folks will take up the practice of the rosary.

Scripture
• Luke 1:26-55; 2; 9:28-36; 24:1-8
• Matthew 1:18-23; 26:26-30, 36-46; 27:22-26
• John 2:1-12; 19:1-5, 26-30
• Mark 1:1-8, 14-15; 15:20-22
• Acts 1:6-12; 2:1-3

Online rosaries
• comepraytherosary.org/
• virtualrosary.org/

Books
• The Rosary: Mysteries of Joy, Light, Sorrow, and Glory by Alice Camille (ACTA Publications, 2003)
• The Rosary Prayer by Prayer: How and Why We Pray the Christ-Centered Rosary of the Blessed Mother by Mary K. Doyle (ACTA Publications, 2006)

The words immaculate conception are not in the Bible, yet the teaching that Mary was conceived without sin carries the weight of dogma: a Greek term for “what seems right.” A dogma is considered an infallible teaching. According to the First Vatican Council (the "other" Vatican council rarely talked about), a dogma must be 1. Contained in scripture or part of post-biblical tradition; 2. Explicitly proposed as a divinely revealed belief; and 3. Issued as a solemn decree that can be later developed but not deliberately rejected without risk of heresy.

Wow. That means this teaching about Mary’s beginnings is essential to Catholic understanding. Yet none of the four gospels mentions Mary’s origins. Even her parents, Joachim and Anne, are not named. The genealogies of Jesus in Matthew 1 and Luke 3 trace Joseph’s line.

We get our early stories about Mary from that “post-biblical tradition” alluded to above, records of hazy origin like The Birth of Mary, the Protevangelion of James, and The First Gospel of the Infancy of Jesus. While these documents didn’t make the cut when the canon of scripture was set, they remain valuable windows into the way early Christians expressed their beliefs. One thing they make clear: The early church had a powerful sense that the Incarnation-event bound Jesus and his mother in a singular, physical infusion of divine grace.

That helps us appreciate why the Immaculate Conception—celebrated as a feast in the 11th century and officially introduced as dogma in 1854—still represents a very early church understanding. Theologians point to scripture passages that validate the cosmic preparation of Mary for her role: Genesis 3:15 (sin will be conquered by a woman); Luke 1:28 (Mary is favored); Luke 1:42 (Mary is blessed among women).

The 12th-century theologians Anselm and Bernard of Clairvaux as well as Aquinas and Bonaventure in the 13th century voiced concern that a sinless Mary would put her outside of the need of Christ’s universal salvation. Do we really want to say she didn’t need saving? The Franciscan Duns Scotus resolved the objection by saying Christ could save in two ways: by lifting up the sinner or by preserving one from sin altogether. Mary remains the only person so far identified in the latter category.

Consider this: There was a time when your life and your mother’s were literally inseparable. For the sake of that time when Mary and Jesus shared life together in her body, why wouldn’t God prepare the way?

Scripture
• Genesis 3:15; Luke 1:28, 42

Online
• Ineffabilis Deus, Pope Pius IX’s Apostolic Constitution on the Immaculate Conception, December 8, 1854
• The Second Vatican Council’s Dogmatic Constitution on the Church (Lumen Gentium), chapter 8, “The Blessed Virgin Mary, Mother of God in the Mystery of Christ and the Church”

Books
• The Virgin Mary and Theology of the Body edited by Donald H. Calloway, M.I.C. (Marian Press, 2005)
• Lost Scriptures: Books That Did Not Make It into the New Testament edited by Bart D. Ehrman (Oxford University Press, 2003)
• Tradition and Incarnation by William L. Portier (Paulist Press, 1994)