Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Shaykh Tusi, full name: Abu Jafar Muhammad Ibn Hassan Tusi, known as Shaykh al-Ta ifah was a prominent Persian scholar of the Shi''a Twelver Islamic belief. Al-Shaikh al-Tusi grew up in Tus and began his studies there. In 408 A.H. he left Tus to study in Baghdad. There he first studied under al-Shaikh al-Mufid, who died in 413 A.H. Leadership of the Shi''ite scholars then fell to al-Sharif al-Murtada. The latter remained in this position until his death in 436 A.H. During this time al-Shaikh al-Tusi was closely associated with al-Sharif al-Murtada. His vast scholarship and learning made him a natural successor of al-Sharif al-Murtada as the leading spokesman of Shi''ite Islam. So impressive was his learning that the Abbasid caliph, al-Qadir, attended his lectures and sought to honour him.