This book is a collection of essays on the concept of iqtisad, inspired by the path-breaking contribution of the late Imam As-Sayid Muhammad Baqir As-Sadr. It outlines the characteristics of the Islamic economic system, and presents an in-depth theoretical analysis of how a sound banking system can perfectly operate without utilizing interest as mechanism for allocating financial resources. Muslim contributions to economics, which have been ignored throughout the past centuries, are explained.