In Islamic philosophy, the qalb (Arabic: قلب), or heart, is the origin of intentional activities, the cause behind all humans' intuitive deeds. While the brain handles the physical impressions, qalb (the heart) is responsible for deep understanding within the sadr (the chest). Heart and brain work together, but it is the heart where true knowledge can be received.
In Islamic thought, the heart is not the seat of feelings and emotions, but of rūḥ (Arabic: روح): the immortal cognition, the rational soul.
Qalb (قَلْب) literally means to turn about. So what is the connection between “turn about” and “the heart”? When something turns about, it does not remain the same and so does our heart. Our feelings and thoughts change all the time and that is why it is called Qalb (قَلْب).
In the Quran, the word qalb is used more than 130 times.
Qalb also refers to the second among the six purities or Lataif-e-sitta in Sufi philosophy. To attend Tasfiya-e-Qalb, the Salik needs to achieve the following sixteen goals.