Madonna depictions can be seen in early history around the world; consider the ancient Hindu and Egyptian Madonnas. They have evolved through time. When did the Madonnas of Europe first include the symbol of the crescent? It seems to be at the same time as the fall of the Byzantine Empire in the 1450s.
The earliest painting I could find depicting Mary and the Cresent symbol is the "Madonna on a Crescent Moon in Hortus Conclusus" ~1450s by the "Master of 1456." Hortus conclusus is latin for "enclosed garden." If there are earlier examples please comment below.
The concept of a garden brings up other symbols such as sun dials, topiary, horticulture, the Garden of Eve, medicinal plants, roses, bees, butterflies, birds and snakes. But what is the difference between an enclosed and a non-enclosed garden? I think it may have to do with the inner cultivation of the Divine Light versus external forcing of nature. It is also a reference to Virginity and parthenogenesis: fertilization from within rather than an external act.
"A garden enclosed is my sister, my spouse; a garden enclosed, a fountain sealed up." Song of Solomon 4:12.
