Hazrat Imām Ghazāli Sahib رحمه الله has mentioned in Tablighe Deen that the heart and limbs have a special connection; the effect of all actions performed by the limbs reach the heart. Therefore, as long as the movement of one's limbs do not reach the level of moderation, the heart cannot attain complete illumination and potential. The heart is like a mirror. A mirror can truly reflect the light of the sun when three factors are found:
1. The mirror has to be polished.
2. The surface of mirror has to be illuminated.
3. The surface of the mirror has to be smooth (not warped).
Similarly, when these three qualities are found in the heart, it will become the reflection of Allah Ta'ala's Special Mercies:
1. The heart is polished by abstaining from lustful desires and evil character.
2. The heart is illuminated by Zikrullāh and Ma'ārifah (recognition of Allah Ta'ala جل جلاله).
3. The warped nature of the heart is removed by bringing the actions of the limbs into equilibrium (I'tidaal).