Herman Hugo's Pia desideria, a spiritual emblem book published in Antwerp in 1624, was the most popular religious devotional book of the seventeenth century. It went through 42 Latin editions and was widely translated up to the 18th century. The work indicating three paths to salvation, through purification, illumination and union. It consisted of a series of 45 emblems by Bolswert with accompanying verses by Hugo, subjects for meditation on the theme of spiritual love.