This Jesuit is best known for his book of maxims, El Oraculo Manual, translated into English as The Art of Worldly Wisdom (among other names). The young George Washington even went to the trouble of copying many of his sayings into his journal. Definitely some good advice here for being as clever as serpents!
However, thanks to our books.google.com friends, we can also read his less known work El Comulgatorio, translated by Mariana Monteiro as Sanctuary Meditations.
This looks like a pretty good devotional book to take to Mass with you. Drawing on Scripture stories, and in his characteristic plain but eloquent style, Gracian encourages you to improve your mental attitude towards God. There are meditations to encourage humility, and others to give confidence. Some examine gospel people’s attitudes towards Christ, and still others deal with Old Testament types and customs. Finally, with the blunt practicality of the old devotional books, he includes a meditation for receiving viaticum at the point of death. So yeah, you’re ready for anything….