We’ve added several items on the topic of vocation to this site: (1) Summary of the Catholic Church’s Teaching on Vocation
(2) Classic Texts of the Church Fathers and Doctors on Vocation
(3) Some texts by Thomas Aquinas on Vocation to Religious Life
(Update: these texts dealing specifically with the Catholic understanding of vocation have been moved to the website Paths of Love–the links will take you to the new site)