As already stated, the Quran has described three stages of knowledge: 'ilm al-yaqin, ain al-yaqin and haq al-yaqin. Of these, 'ilm al-yaqin is knowledge of a thing acquired inferentially as we conclude the existence of fire from the presence of smoke in a place without witnessing the fire. But if we see the fire itself, our knowledge of the existence of fire becomes a certainty of the second degree - 'ain al-yaqin. Knowledge of a thing we witness with the eye may, however, be further improved upon through actual experience, for instance, by thrusting our hand into the fire. Thus we reach the highest stage of certainty, which is haq al-yaqin.

The sources which guide us to the knowledge of certainty are reason and information. With reference to those who do not believe in these means, the Holy Quran says:

"Allah does not imposes on any soul a duty (which is) beyond its scope . .. - 2 : 286.

In this verse, God gives us clearly to understand that the doctrines and belief, to which He invites people through His messengers are only such as are within the capacity of human understanding and knowledge, and that He does not force men to bear any burden beyond their strength.

"And they (disbelievers) say: Had we but listened or pondered, we should not have been among the inmates of the burning Fire"~7: 10.

The verses quoted above also point to the fact that a person can acquire the knowledge of certainty through accurate information. For instance, we have not seen London, nevertheless we are certain of the existence of a city of this name because we cannot disbelieve all those who have seen it. Or, though we did not see Aurangzeb yet it is beyond the shadow of doubt that he was one of the emperors who reigned in India.

Thus we can arrive at a certain conclusion as to the reality of a fact or the existence of a thing through hearing when the chain of testimony is strong. The inspiration of the prophets is a source of knowledge provided there has been no interruption in its transmission, and the vehicle through which it is conveyed to us is not of an imperfect nature. But if there are many different accounts of a single event contradicting each other, and they all claim to be based on revelation, the mere acceptance by any sect of some of these documents as of a heavenly origin, and the condemnation of the rest as spurious and fabricated, if not based on a critical inquiry, lends no support to the truth of the facts therein related. A series of such narratives, inconsistent with each other, is utterly incredible and we need no other proof for their rejection. Nor can they be a source of knowledge because they cannot lead to any certain conclusion, being themselves doubtful.

In this connection, it should be noted that the truth of the Quran does not depend merely on its uninterrupted transmission and authenticity, for it proceeds on the basis of reason. It does not compel us to accept its doctrines, principles and commandments simply on the authority of revelation, but appeals to our reason and supplies arguments in support of what it inculcates. It is to this fact that the Holy Book refers when it says that the principles which it inculcates are impressed in the nature of man:

"And this is a blessed Reminder " - 21 : 50.

This blessed Book does not preach strange and novel doctrines, but it is a Reminder of that which is impressed in the nature of man and the laws of Nature.

"There is no compulsion in religion " - 2:256.

To all that which is talked about the Prophet of Arabia offering Islam or the sword as alternatives to the pagan Arabs, this verse is a sufficient answer. Islam does not compel a person to accept its doctrines, but offers reasons for their acceptance.

"And (it is) a healing for that which is in the breasts (a guidance) .. "
- 10 : 57.

This verse means that the Quran is a cure for all spiritual ailments.

The Quran is not a book which derives all its force from being an ancient document, which has been handed down to us through a safe course of transmission, but its real force lies in the sound arguments which it produces and the clear light which it sheds. In the same manner, intellectual arguments which have a sound basis lead a man to a knowledge of certainty. To this, the Word of God alludes in the following verses:

"In the creation of the heavens and the earth and the alternation of the night and the day, there are surely signs for men of understanding. Those who remember Allah standing and sitting and (lying) on their sides, and reflect on the creation of the heavens and the earth: Our Lord, Thou hast not created this in vain! Glory be to Thee! Save us from the chastisement of the Fire" - 3 : 189-190.

Conscience, which is called human nature, is also a source of knowledge. The Holy Book says:

"The nature made by Allah, in which He has created men . . . - 30 : 30.

This impression in the nature of man makes him regard the Almighty as one without any partner, the Creator of everything, and free from subjection to birth or death. Although the knowledge derived from human nature does not appear to be inferential, yet we have called human nature a source of knowledge because it leads to a conclusion by a very fine thread of inference. The Master has charged everything with a peculiar property which it is difficult to describe in definite words, but, when we reflect over it, the inherent property at once strikes the mind. If for instance, we imagine the person of the Divine Being and ponder over the attributes we desire to see in Him and consider whether He should undergo the processes of birth and death and suffering like ourselves, the idea makes us shudder; human nature revolts at it and recoils from it, being unable to bear it. The idea is repellent. The still small voice within us at once speaks out that He, in Whose powers we must completely trust, should be a Perfect Being, free from every blemish and defect. The concepts of God and of the Unity of God co-exist in human nature, and the one is not separable from the other.