At the heart of the monastic spirituality is the development of hesychasm as a means toward achieving an experience of the divine (theosis), and this development proved to be of immense importance in the history of the Orthodox Church. This development of hesychasm, focused on the necessity of ceaseless inner prayer, greatly influenced later Orthodox Church history, spirituality and pastoral counseling. For reasons which will be discussed within this paper, hesychastic spirituality came to the forefront in the fourteenth century, especially through the substantial contribution of Saint Gregory Palamas (1296-1359), and since that time it has played a key role as a renewal movement within Eastern Christianity up to the present day. In his defense of hesychasm prayer, Saint Gregory Palamas formulated a solid theological justification based on the writings of the past Church Fathers, which means that he was in full conformity with the Orthodox Christian tradition.