What is the spiritual heart (Qalb), and how is it different from the physical heart?

The Arabic word qalb carries two meanings. One is the biological heart in the chest that circulates blood. The other is the spiritual heart, a subtle element which finds unison with Allah.

The path of Tasawwuf is a journey to reform the inner self and rid the heart of its ailments, as the Beloved Prophet ﷺ said: "There is a piece of flesh in the body, if it becomes virtuous, the whole body becomes good but if it is ruined the whole body gets ruined and that is the heart." [Sahih al-Bukhari 52]

The heart mentioned in that hadith is not the biological heart, but the connection, the unseen energy to the material heart, which connects the believer to Allah.

The word qalb in the Qur'an and Hadith is used to express mind, thoughts and perception, as well as the physical heart itself. The Qur'an describes the heart as a living entity and refers to it with many attributes: a Divine gift, the locus of faith and piety, the centre for belief, a place for mercy and compassion. It can be enlightened, contented and peaceful, the point where Divine light descends and the subtle faculty through which human beings attain their humanity.

Qalb is the locus for discernment, feeling and knowledge. According to the Qur'an it represents the relationship between the human being and the Lord, and in the words of the Qur'an it holds tadabbur, meaning contemplation, and tazakkur, meaning remembrance. When the spiritual heart is immersed in the love of Allah, the body, being the slave, follows the Shariah and the soul submits to the Lord.