In Spiritual Warfare and the Discernment of Spirits (Sophia Institute Press), Dan Burke has provided a lucid and readable explanation of St Ignatius’ 14 “rules” for how to distinguish negative, unhappy and restless thoughts subtly inserted into our minds by evil spirits. That we live in the midst of spiritual warfare is classic Catholic teaching and St Ignatius has been proved an acute psychologist of our mental discontents over the centuries. Burke’s is not a long book and can be read, with profit, in a couple of sessions.