There's also a whole subtext about the Nursing Mary ("Virgo Lactans")...without bogging everyone down with too much iconographic analysis, images of Mary nursing the Infant Christ often predominantly showed the breast, towards the direction of the viewer. The viewer then could imagine him/herself also being nurtured by the milk of the Virgin (there's all sorts of contemporary texts that expound on Mary's milk as a substance to "feed" one's soul). The period during late Middle Ages/early Renaissance focused on the Virgin as a kind, loving, tender and nurturing intercessor on behalf of mankind; this iconographic motif was one way that this "nurturing" aspect of the Virgin was manifested.