Basic and expanded role of heart
The Qur'an has variously described the role of heart.
Thinking, pondering and comprehending are some of its functions. Thinking means arranging the known date for the purpose of analysis, composition, comparison and evaluation. As the result of this process, general rules and principles are obtained and then applied to particular cases.
Pondering means going into the hidden aspects of the apparent phenomena in order to find the way to the real truth. What we can discover by means of our senses is only a superficial reflection of what is the present appearance of the things. Our senses can neither discover the inner truth directly, nor can they find out the ultimate end of any event.
By means of our senses we can know only what is perceptible and observable, but they do not have enough power to have access to the inner truth. Only pondering, deep thinking and mental analysis can do that.
Hence scientific knowledge must not be based on credulousness, guess and conjecture, superficial judgment and short sightedness. It must be accompanied by correct mental analysis and deep thinking so that the result may be clear, convincing, reliable and fit to be followed.