On The Elucidation of The Marvels of The Heart

Kitab Sharh 'Aja'ib al-Qalb
Book XXI of the Revival of the Religious Sciences
Ihya 'Ulum al-Din
Arabic with English Translation

To appreciate the vaue of this book, there are no better words than Imam an-Nawawi who said that if all the books of Islam disappeared except The Book of Allah and the Ihya, it would suffice you.
This volume elucidates the marvels of the heart. The Imam deals authoritatively with the heart's diseases and their cures.