Islam, in being founded on such a worldview, is a comprehensive and realistic teaching. It considers every aspect of human needs, whether this worldly or otherworldly, physical or spiritual, intellectual or emotional and affectual, individual or social. From one standpoint, the aggregate of Islamic teachings comprises three areas:

1. Principles of belief, that is, things in which it is the duty of every individual to strive to attain belief. The task that man is charged with in this area falls under the heading of investigation and the acquisition of knowledge.

2. Morals, that is, traits that it is the duty of every Muslim to incorporate and adorn himself with and whose opposites it is his duty to shun. The task that man is charged with in this area falls under the heading of self-control and self-moulding.

3. Decrees, that is, rules that relate to the overt and objective acts of man, inclusive of acts with this worldly and otherworldly ends, and of individual and social acts.

According to the Shi'i school of thought, the principles of Islamic belief are five: Tauhid, justice, prophecy, the Imamate, and the Hereafter (ma'ad, the Destination). As regards the principles of belief, according to which each individual is charged with acquiring a right belief, Islam does not regard imitation and blind submission as sufficient; every individual must freely and independently verify the rightness of these beliefs. According to Islam, worship is not confined to physical acts of worship, such as the alms-taxes zakat and khums. There is another kind of worship, and that is mental worship. Mental worship, or contemplation, if directed at man's admonition and awakening, is superior to years of physical worship.

Where Thought Stumbles
The Glorious Qur'an, in summoning us to reflect and draw conclusions, in regarding reflection as worship, and in not regarding acceptance of the principles of belief as sound without logical reflection, has attended to this basic question: Where do the stumbling in human thought arise? What is the taproot of error and straying? If one wishes to think straight and avoid error and deviation, what must one do?

In the Glorious Qur'an, a series of phenomena are named as the occasions and causes of error and straying: reliance on supposition, psychical tendencies and desires, haste, traditionalism, and obedience to personalities.

Reliance on Supposition Instead of Knowledge and Certainty
The Noble Qur'an, in numerous verses, stringently opposes action based on supposition instead of knowledge and certainty; it says:

"Do not pursue that of which you have no knowledge" (17:36) and "The nature of most people is such that if you try to follow them, they will mislead you, because they rely on supposition (not on certainty) and act solely on conjecture and estimation" (paraphrase of6:116). Modern philosophy has established that this tendency is one of the chief factors in error and confusion.

A thousand years after the Qur'an, Descartes made this recognition the first principle of his logic. He says: "The first of these [precepts to which I have adhered] l was to accept nothing as true which I did not clearly recognise to be so: that is to say, carefully to avoid precipitation and prejudice in judgements, and to accept in them nothing more than what was presented to my mind so clearly and distinctly that I could have no occasion to doubt it."

Psychical Tendencies and Desires
If one wishes to judge rightly, one must preserve a complete impartiality toward the matter under consideration; that is, one must strive to find only reality and submit to reasons and evidence. One must be just like a judge considering a case, impartial to the two sides of the dispute. If a judge has a personal bias toward one side, he will unconsciously pay more heed to the reasons adduced for that side's case. Such a bias will cause the judge to err.

If in his own reflections one fails to preserve his impartiality relative to the negation or affirmation of a matter, if his psychical tendencies are to one side, automatically, without his being aware, the meter-needle of his thought will swing to the side of his psychical tendencies and desires. Thus, the Qur'an terms the desires of the psyche, along with reliance on supposition, one of the factors in thought's stumbling. It says in the Sura Najm: "They follow nothing but supposition and what their own psyches desire" (53:23).

Haste
Every judgement or expression of opinion demands a certain amount of evidence. Until sufficient evidence has been gathered on a question, any son of expression of opinion constitutes haste and occasions stumbling in thought. The Noble Qur'an repeatedly alludes to the paucity of man's stock of knowledge and its insufficiency for some major judgements; it conceives of dogmatic assertions as highly imprudent. For instance, it says: "Only a little knowledge has been given you" (17:85), which is to say that the amount of knowledge and information that has reached us is slight and insufficient for judgement.

Imam Sadiq (peace be upon him) has said:

In two verses of the Qur'an God has singled out His servants and admonished them: first, that they not affirm a thing until they have attained knowledge of it [haste in affirmation], and second, that they not deny a thing until they have attained to knowledge of it-until they have reached the stage of knowledge and certainty [haste in denial]. God says in one verse: "Was not the Covenant of the Book [the book of essential disposition or the revealed books] taken from them that they would not ascribe to God anything but the truth?" (7:169). He said in the other verse: "But they deny what their knowledge does not encompass' (10:39)

Traditionalism and Looking to the Past
In accordance with his first nature, when man sees that a particular thought or belief was accepted by past generations, he automatically accepts it without allowing himself time to consider it. The Qur'an reminds us not to accede to the accepted notions and beliefs of past generations until we have weighed them on the scales of reason, and recommends independence of thought vis-a-vis the beliefs of past generations.

It says in the Sura Baqara, verse 170:

"When it is said to them, 'Follow what God has sent down,' they say, 'No, we follow the customs we found our ancestors to believe in.' What! Even though their ancestors were void of reason and unguided?" (2:170).

Obedience to Personalities
Another of the occasions of stumbling in thought is obedience to personalities. Great historical and contemporary personalities, owing to the proportions of grandeur they assume in others' minds, exert an influence on others' thoughts and wills, to the point of overwhelming them. Others think as they think and resolve as they resolve. Others give up their independence of thought and will to them.