The history of devotion to Mary, Mother of God began in the earliest times of the Church. Soon after the Church Council of Ephesus in 431 A.D., the feat of the "dormition" or death of Mary began to spread. The feat came to be known as the Assumption.
In 1950, Pope Pius XII defined the dogma of the Assumption. At that time he listed the benefits that should flow from this devotion:
a stronger piety toward Mary, the Mother of God,
a more universal conviction on the value of human life devoted to God’s will,
a repudiation of the materialism that diverts body and soul from their lofty goal,
and "finally it is our hope that belief in Mary’s bodily Assumption into heaven will make our belief in our own resurrection stronger and render it more effective."
The images expressed during this feast reflect its history. In its earliest form, the day focused on the mystery of the resurrection as expressed in the death of Mary.