Imam Abu Hamid al-Ghazali is one of the Gifts of Allah to this Ummah. Illustrative of this is that our scholars have titles him Hujjatul-Ilam - The Proof of Islam. He was born in Tus, Persia in 450 AAH and passed away in 505 AH.
A great mujtahid who wrote extensively on many of the Islamic disciplines. His works are recognised by the 'Ulama as the advanced texts of each discipline. His masterpieces include 'al-Mustasfa min 'ilm al-Usul', 'Tahafut al-Falsafiyyah', 'al-Wajiz', and of course 'Ihya 'Ulum al-Din'.