The soul (nafs) is that heavenly essence which employs the body and uses its various organs to attain its goals and purposes. The soul has also other names as spirit (ruh), intelligence (`aql),and heart (qalb) although these terms have other usages as well.
The most important faculties of the soul are:
1. The power of intelligence (al-quwwah al-aqliyyah)-angelic.
2. The power of anger (al-quwwah al-ghadabiyyah)-ferocious.
3. The power of desire (al-quwwah al-shahwiyyah)-animalistic.
4. The power of imagination (al-quwwah al-wahmiyyah)-demoniac.
The function and value of every one of these powers or forces of the soul is commonly well understood. If man did not have the power of reason, it would have been impossible for him to distinguish between good and evil, right and wrong, true and false. If he did not possess the faculty of anger, he could not defend himself against attack and aggression. If the force of sexual attraction and desire did not exist in man, the continued existence of the human species would be endangered. And finally, if man lacked the power of imagination, he could not visualise universals or particulars, and he would be unable to make any inferences based on them.