Badges mark quoted or attributed material (Qur'an, hadith, another author, an opposing view). Unbadged passages are Maulana Wahiduddin Khan's own words.
In ancient traditional times, the heart was regarded as the source of purification and realization (maarifah). But modern scientific research has proved that the human heart is just a pumping organ which causes the blood to circulate. Maarifah and purification are, therefore, mind-based, rather than heart-based. Here the question arises about the significance of certain verses in the Quran which attribute maarifah and purification to the heart. The answer is that the Quran does not refer solely to heart; it repeatedly refers also to the mind: for instance, “We have made it an Arabic Quran, so that you may understand.” (La’aallakum taqilun) (43:3) “This is a blessed Book which we sent down to you (Muhammad) for people to ponder over its messages and for those with understanding to take heed.” (38:29) And, “… in this there are signs for men of understanding.” (20:54) And, “…is there not in this strong evidence for a man of sense?” (89:5) The word used in these verses of the Quran is aql (mind). This being so, the question arises as to how to explain these two differently worded sets of Quranic statements. In this case, according to the rules of grammar, one will be subordinated to the other. The way to apply this principle is to see in whose favour is the additional evidence, and then this additional evidence should be taken in its literal sense and the other will be subordinated to it. In this discussion of the heart and mind, there is additional evidence in favour of the mind, as discovered by modern science. That is why the verses which refer to the mind, will be taken in their literal sense, while the verses which refer to the heart will be taken in a purely figurative sense. In this way, both the words—“heart” and “mind”—as used in the Quran will be held to be synonymous. There are some who hold that the heart has the capacity to think. That is, it is a thinking organ of the human body. But this is just a fallacy. Their claim is allegedly based on a physiological study which shows that there is a link between the heart and mind. But this claim is clearly fallacious. Of course, there is a kind of link between the mind and the other organs of the body. But this link is not a cognitive one. It exists only in a purely physical sense. The truth is that all the organs of the body act under the direction of the mind. None of the organs function independently of the mind. The error of this argument lies in the fact that an ambiguous word, that is, communication, has been used to define this link. The right word to express this matter is direction, not communication. The difference between the two is that the act of direction is unilateral while the act of communication is bilateral. The word “direction” tells us that the mind unilaterally issues directions to the organs, whereas communication means that this activity between the mind and organs of the body is bilateral. p. 21original + quote
In the above argument, first of all the word “communication” was used for contact, then it was concluded that the heart was a thinking organ, whereas there is no scientific basis for such a supposition. The great loss occasioned by this error was that those who believed in the concept of heart-based God-realization were deprived of wisdom, for they were seeking wisdom in the heart, whereas wisdom did not stem from the heart at all. It is to compensate for this lack of wisdom that religionists (those who believe in one religion or the other) resort to concocted stories to make their point. p. 22
Man is a thinking animal. All of man’s activities are controlled by thought. It is believed that man’s personality is shaped by his thinking. It is this thinking faculty which is called the mind. These are the words—synonyms –for the mind that occur in the Quran: Aql, Lub, Fuwad, Hijr, Nuha and Qalb. “Heart” is generally taken in the sense of a major organ of the body, but in addition to this, the word heart is also used in the sense of the mind (aql). The most standard dictionary of Arabic Lisan al-Arab says that “heart” (qalb) is also used in the sense of ‘the mind.’ Farra Nahvi, a grammarian, corroborates this with an allusion to the thirty seventh verse of the fiftieth chapter of the Quran. “There is truly a reminder in this for whoever has a heart, whoever listens attentively.” (The Quran, 50:37) In the Arabic language ‘heart’ is often used for ‘mind’. For instance, “You had no heart (on such and such occasion).” That is, you had no mind. (Lisan al-Arab, Ibn Manzur, vol. 1. p. 687) The truth is that the greatest thing man possesses is the mind. The words “heart” and “mind” are used synonymously with the only difference being that the word aql is used for “mind” in its literal sense, while the word ‘heart’ is used for the mind in a literary sense. In present times, it has been proved that the heart is only the centre of the circulation of the blood, while the mind alone is the centre of thinking. But due to literary usage, even today we use such an expression as wholeheartedly, and not whole-mindedly. This is true also for other languages. p. 23original + quote
The subject of the Quran is not anatomy: its subject is guidance to man. Guidance is totally related to reason and understanding. This being so, wherever the Quran uses the word “heart”, in terms of the subject of the Quran, it is to be taken in the sense of mind or reason. p. 23
When the word “heart” (qalb) has two meanings, one as is generally understood in the sense of heart and the other in the sense of aql (mind) then in such a case the meaning of qalb (heart) used in the Quran, would be determined in relation to the subject of the Quran. In this case qalb in the sense of the heart will not be applicable. Qalb in the Quran will apply to the mind or reason. This is an accepted principle of grammar. This is applicable in both cases, in the Quran as well as in other literature. For instance, if a book written on the subject of anatomy uses the word “heart”, then heart will be taken in the sense of an organ of the body and not mind. p. 24
On the contrary, when the Quran uses the word “heart”, it will be taken in the sense of the mind. In every language one word often has several meanings. Each meaning is relative to its context. For instance, the word deen in Arabic has several meanings. In chapter 1, verse 3, for example, the Quran has used it to mean the Day of Judgement, while in chapter 42, verse 13, the word deen has been used in the sense of religion. p. 24