There is no closer moment between a mother and child than the moment of breast feeding Since the Virgin became the subject of painting, the depiction of Mary nursing Jesus has been the way to show there intimacy and union.
In the Gospel of Luke the good doctor records that Mary remembered and contemplated all the moment of the nativity and infancy of Jesus. As a mother may become as one with the child while nursing, the Virgin was remembering and contemplating her union with God incarnate.
Through experience and practice at the rosary, and letting the grace of God lead me in my understanding of the words and images the rosary meditation stirs up, I have been able to add a great deal of physical sensation to my identification with the characters of the biblical stories. I believe it it within the reach of anyone who is deep in prayer to do this, and that it is the gateway to the stage none as "contemplation" Contemplation is that stage of prayer were one simply listens to the Word of God" or gazes on the Sacred Images or otherwise moves into higher awareness of of the Divine Presence. I believe some of the painters of Sacred Images were in or moving towards this stage when they painted. this has occurred from the most ancient times to modernity.
I have been mediating on the experience of Mary nursing Jesus attempting to overcome the limits of my gender experience in identifying with Mary. And through God's grace I have had some limited success in visualizing and physical knowing the act of feeding Jesus. It may seem impossible to some, but while never having had a crown of thorns on my head, I have had some limited experience of the thorns in meditating on them. I advocate the use of this technique to deepen ones prayer.