The proclamation of this Marian dogma, like the event of Christ, came as a surprise. A surprise is not a casual event. It is an unexpected desired event. When Christ came to this world, it interrupted our logic, but it made sense to our history. It united the fragmented parts of Israel's life, and therefore explained it more than she can herself. So too with the event of the declaration of Mary's Assumption. Scholars can look at the early history of the Church to try to find evidence for such a belief and may find the evidence wanting. Yet, the dogma explains the salvific presence of God in the world, which, in turn, explains our place in the world.
The first thing to recognize is that the Assumption is a revelation of God Himself. The God of Jesus Christ is not a watchmaker but someone who “lifts up the lowly.” God is the main actor of this event and Mary can only participate.
The other aspect of this dogma is that it reflects the logic of the Ascension. Christ ascended into heaven so that he can be near to us. Within the bosom of his Father, Christ sends His Spirit and transforms the bread into His body so that we can be one spirit with Him. We can be one with Christ and each other because Christ detached Himself from us. This is the summit of love, virginity. The fecundity of the Marian fiat is seen in the event of the Assumption: the Virgin becomes mother of all. Christ's declaration to the beloved disciple on the cross is universalized through the Assumption. We can receive Mary as our mother only if she is united with God. Her universal maternity cannot be understood apart from the tender mercy of God for us. We cannot love another person, cannot receive another, if we do not see them as sent from God.
This gives us the reason for the proclamation of the dogma. It came from the devotion of the Church to her Mother. What does the motherhood of Mary mean? The faithful's devotion to Mary is the source of the Church's knowledge of her Assumption. This historical event, at the same time, explains our devotion. The Church, therefore, gave us the reason why the motherhood of Mary is possible: God has lifted up the lowly. Our devotions are not meaningless and unreasonable because the Church has provided the ultimate reason: Christ, the son of Mary, is God.