Islam makes use of three principal means of acquiring knowledge of the world and of the truths of religion, recognizing the validity of each of them within their respective spheres. These three means are: (a) the senses, the most important of which are hearing and seeing; (b) intellect and reason, which arrive at truths in a man­vter at once definitive and certain-albeitwithin a delimited realm, on the basis of particular principles and in accordance with cer­tain conditions; (c) revelation, the means by which specially sulected, exalted individuals receive knowledge from the unseen domain.

The first two means are common to all people, helping them m gain an understanding of the world, and are the effective sup­ports for the comprehension of the Shari'a.'The third way concerns those individuals who have received a special blessing from the \Iwighty, the most evident examples of whom are the Messen­yrs of' God.' The senses can be used as cognitive means only in i he sensible realm; intelligence is useful as regards finite dornairrs; while the realm of revelation is infinitely more vast, casting light ''o diverse areas, including religious beliefs and practical obligations.
The Holy Qur'an has several versca relating to these means, of which we shall cite here two examples. Regarding the senses and the intellect, it states: And God hroughl you forth from the wombs of your mothers while ye knew nothing, and He gave you, hearing and sight and hearts (afida), that ye may give thanks. (Sura al-NaEI, xvr:78)
The word afida in Arabic is the plural of fu'ad; it denotes the inner sphere within which the human faculties of hearing, seeing and intelligence are articuiated. At the end of this verse, God corn­mands gratitude; this shows that man must benefit from all three faculties, which are to be seen as blessings: the true meaning of gratitude is to be grateful for every blessing, in a manner appro­priate to the blessing.
As regards revelation, it states: And We sent not heforr tizer~ but me-ra [as Our Messengers] whom We inspired; so ask the people of the remembrance if ye know not. (Sura al­Nattl, xvr: 43)
The religious man, in acquiring knowledge of the world and of religion, benefits from the senses. But sensible perceptions only constitute the empirical foundations of intellectual _judgement; be benefits from his irrtcIiect hy acquiuinl; knowledge of God, His attributes and His acts. The proper utilization of each of these three means, cs-ithin their respective fields, proves their efficacy in the disclosure of the truth, at differwa dcyrees.2
The substance of the message delivered by God's Prophets can be sumrnarized under two headings, belief and action. As regards the realm of belief, there is first faith in the reality of God, in His attributes of Beauty (jamdl) and Majesty ( jalal) , and in His divine acts.3 Likewise, as regards action, there are duties and commands, so ordained that man might conduct both his individual and so­cial life according to the divine norm.
The aim of right belief is knowledge and certainty; naturally, it is only decisive self-evidence (hujja) that can lead the way to this certainty. Thus, it is incumbent on every Muslim to attain cer­taintv in his beliefs on his own account-he cannot simply resort m the imitation (taqlid) of others in this realm. As regards duties and commands with respect to actions, their goal is to make our lives conform with our beliefs. In addition to certainty, one must have recourse to ways of acting that are confirmed by the Shari'a; this, in turn, means that one must have recourse to a mujtahid, an expert on the Shari'a. This is a subject which will be further considered below.
We benefit from all valid modes of cognition in our comprehen­sion of beliefs and religious commands, but the chief means of affirming these principles are the intellect and revelation. By the word `revelation' we mean the heavenly book, that is, the Holy Qur'an, along with the sayings of the Prophet that reach us through verified chains of transmission. The sayings of the Imams of the ahl al-bayt, which will be considered below, are also classi­fied under the heading of `Sunna', as they, too, form part of the divine proofs.
Intellect and revelation are mutually corroborative proofs: if on the one hand, decisive intellectual judgement confirms the veracity of revelation, on the other hand revelation confirms the validity of the intellect in its proper domain. In many places, the Holy Qur'an calls upon us to use our intellectual discernment; it invites man to reflect upon and contemplate the marvels of crea­tion, and even goes so far as to enlist the support of the intellect in order to substantiate the content of its own call to accept the truth of God and of Islam. No other revealed book bestows so much value upon the intelligible demonstration of beliefs and doctrines; such reasoned demonstrations abound in the Qur'an.
The Imams of the ahl al,-bayt have also stressed the importance of the evidence provided by the intellect in those domains where the intellect is competent to judge; the seventh Imam, Musa al-Kazitn, referred to revelation as outward evidence and intelligence as inward evidence.4
Insofar as revelation is a definitive guide, and the intellect is an inner light, placed within every individual by God, there should never be any incompatibility between these two divinely ordained sources of evidence. If any opposition does arise between them, however, we must deduce from this opposition either a lack of comprehension on out part as regards the religious point in ques­tion, or an error in the premises of our logical reasoning. For God, in His infinite wisdom, could never call upon man to follow two contradictory paths.
Just as there is no real contradiction between intellect and rev­elation, so between science and revelation there should be no contradiction; if there be an apparent incompatibility between them in certain areas, it again has to be said that either our un­derstanding of religion in those areas is deficient, oor else that science has not attained definitive certainty in those same areas. In large part, it is this latter case that causes the divergence be­tween science and religion-scientific hypotheses and assumptions being rashly accepted as verified science, and then posited as refu­tations of certain religious principles.
In respect of laws, which govern the order of existence---laws, which are objective and independent of our thought and imaginationthey, are definitive arid permanent realities. This means that if mankind comes to discover, by means of one of the paths of cog­nition, a given aspect of reality as being absolutely true, then we must say that it is true in an unconditional and permanent way. If, in the process of discovering some aspect of reality, a part of the knowledge resulting therefrom conforms to the truth, while 1,111­other part does riot, that part which is true is always going to be true; for a change in the environmental conditions does not ef­fect a change in universal realirv. In other words, the real import of the concept of `relativity' as regards existence is that a truth that is valid in one period of time and invalid in another period, oannot be regarded as truth at all. If two times two equals four, it will always and unconditionally be so, and if it does not, then it will never do so, in an equally absolute manner. Knowledge can­not be at one with the truth in one domain and in another be urroneous.
`Relativity' in respect of knowledge, is [conventionally] under­stood to mean that reality has no existence independent of human thought and ratification. For example [applying this concept to the political domain], those societies which are not inspired by divine revelation as regards government have the right to decide upon policies with unrestricted freedom. If they agree on a par­ticular policy one day, for as long as they maintain agreement, this policy will be regarded as right and true; but if they agree later to oppose that policy, then `truth' will appear in the form of the second policy. In fact, each of these two contradictory poli­cies will have been assimilated as 'true' according to the intellectual capacity of the individual. On the other hand, as regards those principles that are considered as independent of one's mind, possessing specific, objective qualities and definite boundaries­once they are correctly grasped and situated within one's cognitive horizons, they will always and unconditionally be correct, valid and reliable; just as, conversely, opposition to them will always, and necessarily, be false and unfounded.

Writer: Ayatullah Ja'far Subhani