From Fr. James Coles blog, Scholé 
All the things we say about her could be said about us. But will they?
The third of the great feasts of the summer is the commemoration of the death of the Most Blessed Virgin Mary. This, from the liturgical point of view, is the most important of the feasts dedicated to the Theotokos (Greek for God-bearer).
Many features of this feast are taken from other feasts dedicated to the Theotokos. Thus the gospel for matins tells of Mary’s visit to Elizabeth (Luke 1:39-56). The epistle (Phil 2:5-11) and the gospel (Luke 10:38-42; 11:27-28) for the liturgy are those that are read for September 8, the day of Mary’s nativity. It should be noted that there is no mention in the scriptural passages regarding her death. It is in the songs attached to the feast where we find the special significance.
This significance is twofold and is given exact expression in the phrase, “the source of life is laid in the grave and her tomb becomes a ladder to heaven.” This first part, “the source of life is laid in the grave” indicates that we are commemorating her death. We also remember the deaths of John the Baptist, the apostles and the martyrs. But we call her the “source of life” so we know that more is going on today than simply remembering a saint’s death. The Church, beginning with the glorious disciples knew the Mother of God to be a mortal woman and at the same time the Mother of God. She wasn’t more than human and yet she became the tabernacle that held God. But this feast is much more than just an annual commemoration of her death.
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