Know your enemy, it is said. The passions and those who help them take root are the seed of the devil. The fight against this seed lasts one's whole life, and only he who turns to God will emerge victorious. But where are we to learn the tactics for this fight? Drawing on the experience of the Church and the works of the Holy Fathers, Priest Daniel Sysoev explains how sin works in a persons soul, and how to combat it. This book will provide the reader with food for thought regarding the need for concentrated effort to cleanse one's heart for God.