Mehdi Amin Razavi Aminrazavi 
Suhrawardi and the School of Illumination [PDF ebook] 

Shihab al-Din Yahya Suhrawardi, also known as Shaikh al-ishraq or the Master of Illumination, lived in the sixth century AH / twelfth century CE.
His thoughts form a consistent and coherent philosophical system, and a close study of his writings in Persian reveals a theory of knowledge generally called ”Knowledge by Presence”. The elaborate web of myth and symbolism in Suhrawardi”s philosophy articulates his theory of knowledge, an important subject in the ishraqi school of thought.
Suhrawardi, who claims first to have discovered the truth and then embarked on a path to find the rational basis of his experiential wisdom, represents a thinker who tried to reconcile rational discourse and inner purification.