Rather than being shrouded in mystique, reduced to a transactional asceticism, or stripped down to mere piety, theosis is the transformation of the human person by grace, as it works in their will to move them in ever increasing freedom towards God. Gleaning from the Patristic wisdom contained in such works as the Philokalia, this short manual seeks to lay out the necessary practical framework for the systematic cultivation of theosis by connecting theoretical comprehension together with clarity of application. It aims to present the basics of theory and praxis, and the logic of their connection, in such a way that a person can faithfully understand and earnestly apply themselves to the "upward call of God in Christ Jesus." There is not another life with which we might undertake these efforts, therefore anyone who desires all that God has purchased for them by His Blood is urged thus to apply themselves to the exercise of theosis. From the tumult of the passions to the transformative nature of faith, and from practical apophaticism to the insight born of theoria, the stepping stones of watchfulness, stillness, and ceaseless prayer lead the grace-led person onward in their mystical union with the Lord Jesus Christ. The present work thus hopes to assist the faithful reader in fulfilling this, God's Gospel call to abide in Him and to be indwelt by Him.