Our focus in this section is on Ghazzali's topic of Acquisition of Knowledge. This grounds the basis of the epistemology in Ihya. Of importance here to note is the primacy that Ghazzali attaches to religious knowledge, and thus treats revelation as premised in the Qur'an and Sunnah, as the foundation of Islamic epistemology.2 Such a category of knowledge is termed as Fard Ayn. Its total area comprises the praiseworthy sciences. On the other hand, there are highly recommended but not obligatory sciences that are necessary for the welfare of society. This branch is called Fard Kifaya. Disciplinary subjects, such as mathematics, natural sciences, social sciences, medicine etc. are taken up by this area. Islamic epistemology is further extended to comprise also the sources of social consensus, called Ijma, arising from discursions on specific matters dealing with the knowledge of Qur'an and Sunnah. Yet a fourth source of Islamic epistemology is taken up. This comprises the sayings of the companions of the Prophet Muhammad, as the companions witnessed the actual enactment of revelation to the Prophet.

In Ghazzali's opinion, deriving from his devotional practice of Sufism, real knowledge of sciences lies as a secret to the heart and mind. The heart and mind can fathom these secret recesses a little at a time, only by associating with Divine knowledge the attributes of God, the understanding of His creative purpose, the meaning of prophethood in these functions and in the eternal link between temporal life and hereafter. The creative order with the purpose of knowledge, the gradual unveiling of the mind and heart to the knowledge of Divine attributes, moral self-reformation, are seen to establish the link between such revealed premises and the real world of human conduct, cognition. This functional relationship between revelation and reality is called in Ihya as practical religion. The Prophet Muhammad said in this regard, "Take to learning as far as possible, but God will not give its rewards till you translate it into action."

In the area of practical religion, Ihya goes on to define the rules of moral conduct in commerce, earnings, work and transactions. A model of the social economy is laid down on the premise of the moral self-actualization. This is shown to be the linkage between the commerce of the temporal world and the rewards of hereafter. Three classes of transacters are categorized. First are those who earn livelihood only for this world and reject the returns of hereafter in relation to temporal actions. Second, there are those who focus life's purpose solely for the hereafter and their link to worldly activities is by way of marginal earning of livelihood. Thirdly, there are those who are midway between the above two. The first case negates the model of Ghazzali's social economy. The second two comprise the model of the social economy. Hence, the world is seen as the groundwork for attaining felicity in hereafter through the benefits that practical religion in this case bestows on the Islamic social economy.

The psychological uplift of the heart and mind toward acquisition of knowledge is brought out in Ihya by way of stages of growth of moral self-consciousness. The ultimate spring of this moral consciousness is shown to be premised in the Precept of Oneness of God (Tawhid). Yet here too, there are stages for comprehending the essence of Tawhid.

The Precept of Tawhid is taken up in four stages in Ihya. First there is the outer husk of Tawhid, which is manifested in terms of the utterance of God's Oneness. The second stage is to confirm that proclamation of Oneness by the heart. The third stage is to feel the essence of Tawhid as an inner light, and this power is said to come to truly God-fearing people. The fourth stage is to have the feeling of being in the presence of God, which is the highest stage of moral consciousness. In all, the epistemology of Ihya is shown to be premised totally on the roots of Tawhid, and then to externalize this primordial root into action. In this way comes about the meaning of practical religion as a sum-total of belief forming moral consciousness, defining human conduct in practical life and experience.

Finally, it is important to note how Imam Ghazzali treats the relationship of temporal life with hereafter in his epistemology.6 The following saying of the Prophet is invoked to convey the moment of the supreme most proof of self-actualization and its rewards when God will reveal His vision to the believers in hereafter. This will indeed prove to be the moment of fullest manifestation of perfect knowledge as embalmed in God Himself and presented to creation in small flows at a time. Flows would ensue in this way until the time of the Divine Vision in hereafter. The Prophet's saying in this regard is as follows: God will fulfil His promise to the believers when He will lift the heavenly screen and the believers will see the Glorious God in the fullness of gaze. At that time, all bestowed heavenly enjoyment and happiness will be forgotten for this lofty experience. There will be no limit to happiness acquired from such Divine presence. Thus, perfection of knowledge is equated with this supreme most event and is shown to be derived from the foundation of Tawhid to its transformation to practical religion through the attainment of moral consciousness. 

We can now derive the key points of the above summary of Ihya in respect to the foundation of knowledge. The key points here are relationally expressed as follows:

(Tawhid, Risalah, Ijma, Lives of the Companions of the Prophet) Practical Religion Hereafter...(1)

Risalah means the life of the Prophet Muhammad taken up in its entirety of Sunnah (actions) and Ahadith (sayings). Ijma means social consensus arising from the epistemological foundations of the Qur'an and Sunnah.

In this relationship, the intensity of Islamic socio-scientific movement across stages depends upon the depth of belief and moral consciousness towards discovering the inner secret of the sciences. This in turn is shown to relate belief to external conduct, without which a comprehension of reality remains impossible.