I then examined what knowledge I possessed, and discovered that in none of it, with the exception of sense-perceptions and necessary principles, did I enjoy that degree of certitude which I have just described. I then sadly reflected as follows: “We cannot hope to find truth except in matters which carry their evidence in themselves—that is to say, in sense-perceptions and necessary principles; we must therefore establish these on a firm basis. Is my absolute confidence in sense-perceptions and on the infallibility of necessary principles analogous to the confidence which I formerly possessed in matters believed on the authority of others? Is it only analogous to the reliance most people place on their organs of vision, or is it rigorously true without admixture of illusion or doubt?”

I then set myself earnestly to examine the notions we derive from the evidence of the senses and from sight in order to see if they could be called in question. The result of a careful examination was that my confidence in them was shaken. Our sight for instance, perhaps the best practised of all our senses, observes a shadow, and finding it apparently stationary pronounces it devoid of movement. Observation and experience, however, show subsequently that a shadow moves not suddenly, it is true, but gradually and imperceptibly, so that it is never really motionless.

Again, the eye sees a star and believes it as large as a piece of gold, but mathematical calculations prove, on the contrary, that it is larger than the earth. These notions, and all others which the senses declare true, are subsequently contradicted and convicted of falsity in an irrefragable manner by the verdict of reason.

Then I reflected in myself: “Since I cannot trust to the evidence of my senses, I must rely only on intellectual notions based on fundamental principles, such as the following axioms: ‘Ten is more than three. Affirmation and negation cannot coexist together. A thing cannot both be created and also existent from eternity, living and annihilated simultaneously, at once necessary and impossible.’” To this the notions I derived from my senses made the following objections: “Who can guarantee you that you can trust to the evidence of reason more than to that of the senses? You believed in our testimony till it was contradicted by the verdict of reason, otherwise you would have continued to believe it to this day. Well, perhaps, there is above reason another judge who, if he appeared, would convict reason of falsehood, just as reason has confuted us. And if such a third arbiter is not yet apparent, it does not follow that he does not exist.”

To this argument I remained some time without reply; a reflection drawn from the phenomena of sleep deepened my doubt. “Do you not see,” I reflected, “that while asleep you assume your dreams to be indisputably real? Once awake, you recognise them for what they are—baseless chimeras. Who can assure you, then, of the reliability of notions which, when awake, you derive from the senses and from reason? In relation to your present state they may be real; but it is possible also that you may enter upon another state of being which will bear the same relation to your present state as this does to your condition when asleep. In that new sphere you will recognise that the conclusions of reason are only chimeras.”

This possible condition is, perhaps, that which the Sufis call “ecstasy” (“hal”), that is to say, according to them, a state in which, absorbed in themselves and in the suspension of sense-perceptions, they have visions beyond the reach of intellect. Perhaps also Death is that state, according to that saying of the Prince of prophets: “Men are asleep; when they die, they wake.” Our present life in relation to the future is perhaps only a dream, and man, once dead, will see things in direct opposition to those now before his eyes; he will then understand that word of the Koran, “To-day we have removed the veil from thine eyes and thy sight is keen.”

Such thoughts as these threatened to shake my reason, and I sought to find an escape from them. But how? In order to disentangle the knot of this difficulty, a proof was necessary. Now a proof must be based on primary assumptions, and it was precisely these of which I was in doubt. This unhappy state lasted about two months, during which I was, not, it is true, explicitly or by profession, but morally and essentially a thoroughgoing sceptic.

God at last deigned to heal me of this mental malady; my mind recovered sanity and equilibrium, the primary assumptions of reason recovered with me all their stringency and force. I owed my deliverance, not to a concatenation of proofs and arguments, but to the light which God caused to penetrate into my heart—the light which illuminates the threshold of all knowledge. To suppose that certitude can be only based upon formal arguments is to limit the boundless mercy of God. Some one asked the Prophet the explanation of this passage in the Divine Book: “God opens to Islam the heart of him whom He chooses to direct.” “That is spoken,” replied the Prophet, “of the light which God sheds in the heart.” “And how can man recognise that light?” he was asked. “By his detachment from this world of illusion and by a secret drawing towards the eternal world,” the Prophet replied.

On another occasion he said: “God has created His creatures in darkness, and then has shed upon them His light.” It is by the help of this light that the search for truth must be carried on. As by His mercy this light descends from time to time among men, we must ceaselessly be on the watch for it. This is also corroborated by another saying of the Apostle: “God sends upon you, at certain times, breathings of His grace; be prepared for them.”

My object in this account is to make others understand with what earnestness we should search for truth, since it leads to results we never dreamt of. Primary assumptions have not got to be sought for, since they are always present to our minds; if we engage in such a search, we only find them persistently elude our grasp. But those who push their investigation beyond ordinary limits are safe from the suspicion of negligence in pursuing what is within their reach.