This thesis seeks to study in depth the influence of al-Ghazäli's life, in particular his search for true knowledge, on his theories concerning the psychological dispositions of man, and attempts to clarify the distinctive contribution of his psychological ideas to an understanding of the human personality. The first chapter presents a discussion of al-Ghazali's life against the background of the religious milieu of his time. The second chapter examines his al-Mungidh min al-dalil. The third chapter attempts to provide a general outline of al-Ghazäli's teachings and a summary of the approach he adopts in his magnum opus Ihya `ulum al-din. In the fourth chapter, an assessment is made of the theories of soul of three major Greek philosophers; Plato, Aristotle and Plotinus. This is followed by Islamic theories of soul: those found in the Qur'an, those of al-Färäbi and Ibn Sinä, and finally al-Ghazäli's theory of soul. The final chapter examines briefly al-Ghazäli's concept of happiness and attempts to analyse the spiritual dynamic inherent in al-Ghazali's theory of the soul and how this is related to his views on the human personality. While much other research has been done on al-Ghazäli's ideas concerning the psychological dispositions of man, this study attempts to show by detailed argument that al-Ghazli's psychology has distinctive features which declare his originality.