St Luke tells us about three significant forty-day periods in the life of our Lord. These are:
-the time between the Nativity and the Presentation in the Temple (Luke 2:22)
-the time that Jesus spent in the desert after His baptism (Luke 4:1-2)
-the time between the Passion and the Ascension of our Lord (Acts 1:3)
It would seem to be the case that the period in the wilderness was a necessary final preparation before the Messiah began His mission and that the period after the resurrection was a necessary final preparation before the Apostles undertook their mission, to proclaim the Good News to the world. I would argue that the first period constituted a necessary preparation for Mary before she undertook her mission as the Mother of God present in the flesh, Emmanuel, God with us.

The forty-days had an explicitly Marian dimension in that they constituted the time required for Mary to purify herself, according to the Law of Moses, after the birth of a son. Of course strictly speaking she could have dispensed with the requirement (as her Son could have done with circumcision on the eighth day) because the Law was only the shadow of things to come (Colossians 2:16-17) and the reality had now come in the form of the infant Christ. However since He was born of a woman, born under the Law (Galatians 4:4) it was seemly that the provisions of the Law should be adhered to until our Lord completed His mission on the cross at Calvary.

These days, though, were much more than the formal keeping of an outward legal prescription. They were a time of great and never to be repeated joy for the Blessed Virgin…. click here to read more