Purification of the Heart, as its title states, is a course on the vessel of human spirituality, character, and morality -- the heart. The suffering and problems that we confront in our lives on a personal and even global level actually come down to the condition of the heart. Muslim scholars throughout history have written extensively on this topic, as prompted by the well-known statements of the Prophet (peace be upon him) and verses of the Quran. In essence, Purification of the Heart is a course on the "Greater Jihad" -- as it has been called by illustrious learned men and women of Islamic civilization -- our struggle to become better human beings, luminaries of faith and morality.