Dr. Harry Boosalis, in this concise text, presents us with the Scriptural and Patristic teaching of the Church on the heavenly hosts of angels, the devil and his demons, and the enigma of evil. He offers a rich deposit of Tradition in simplified language, in a clear and concise style, but with an extensive body of scholarly documentation in the footnotes. This book is invaluable to our understanding of our faith, essential in our spiritual struggle, and so helpful in drawing us closer to Christ. It reads easily, as if the professor were speaking to us in person. Professor Boosalis takes a very rich and complex tradition and makes it understandable, offering us hope from what we learn. Reading this book is frightful yet reassuring, a journey and a joy.