Our Lady is presented in a procession of the Holy Sacrament on the occasion of the inauguration of the Basilica of Santa Maria Maggiore in Rome. According to legend, Our Lady appeared to Pope Liberius (+366) and to a Roman patrician with the message to build a church on the Esquilinus. The exact place would be indicated by the snow that would be wallowing in the middle of the summer. We see the bright light of the appearance in one of the houses. At the request of church master Pauwels van Praet and his wife Anna van Hertsberghe, the artist made a painted representation of the snow wonder and the foundation legend.