Saint Paisius Velichkovsky (1722-1794), also known as Saint Paisius of Neamts, lived a monastic life in Ukraine, Romania and Greece (Mt.Athos). He was a man of fervent prayer, a promoter of Jesus Prayer, an ascetic monk, the author of the first translation of Greek Philokalia, a teacher of spiritual improvement, a great reorganizer of large monastic communities, a wise and loving abbot, and a Saint with many outstanding gifts from God. By his work and writings, he ties in a marvelous manner the heritage of the Holy Fathers of fourth to fifteenth centuries to the three great hesychastic centers of the eighteen century (Mt. Athos, Moldo-Vlachia, Russia) and to the origins of Orthodox Christianity in North America (St. Herman of Alaska). The effect of Paisianism and Post-Paisianism on the spirituality of the monastic and laity life is obvious for the whole period from the eighteenth century until today. Contemporary with the Era of Reason in Western Europe marked by Enlightenment (Voltaire, Diderot, Rousseau), Saint Paisius defended an Era of Faith in Eastern Europe, which today gives a firm riposte to the Apostasy so obvious in Occident. This book analyzes Saint Paisius' life and work and also some important Paisian moments from the nineteenth and twentieth centuries: in Romania (Saint Callinicus of Chernika and the "Burning Bush" Movement), in Russia (Saint Seraphim of Sarov and Elders of Optina), and in America (Saint Herman of Alaska and Father Seraphim Rose of Platina). Comments are made on the importance of practicing Jesus Prayer in the daily life of every Orthodox Christian.