Mancipium Mariae

Mancipium Mariae is a Christian devotion.
Its rules, referring to older traditions, were formulated from the inspiration of Jesuit Kasper Drużbicki in following works:

Franciscus Phoenicius, Mariae mancipium, Lublin 1632
Jan Chomentowski, Pętko Panny Maryjej albo sposób oddawania się Błogosławionej Pannie Marii za sługę i niewolnika, Lublin 1632

In ancient Rome, mancipium meant the relation of subjection of one person to another, existing because of mancipatio, as well as a person subjected thus.
The devotion consisted on the act of yielding oneself prisoner to the Mother of God - of subjection to her will. Each slave of Mary had also the duty of praying a litany in the morning and evening and an office on Saturday. The sign of the slavery was a fetters-shaped chainlet with the inscription ego mancipium Mariae.
This sort of piety gained a great popularity in the age of Baroque and had a significant impact on the development of Marian veneration in the Church.