Know that all that Allah has introduced into humans is intended to benefit them.
Thus, certain desires can help him to attract what is beneficial to him. This is the case of the desire for food, for example. Others help him to repel what could harm him, such as the ability to get angry in particular.
That being said, when the desire for food becomes excessive, it turns into harmful gluttony. Likewise, anger, when unchecked, becomes harmful.
The objectives of this book are to apply, on the mind and the heart, the principles of sound reason and rectitude, to channel the desires so that they are not harmful, and to cure the passions under which the we act but who oppose the laws of intelligence and righteousness.
Ibn Al-Jawzi
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