In his magisterial two volume work, The Matter with Things, psychiatrist, philosopher, and Oxford literary critic Iain McGilchrist draws on his expertise in brain science to explore the relationship between reason and emotion. These two cognitive faculties are often seen as strongly opposed to one another. McGilchrist, however, questions this.

He writes:

Emotion is not, as some Enlightenment philosophers thought, necessarily an impediment to reason, but an essential component of it. If you need a demonstration, the patient 'Elliot' reported by Antonio Damasio will serve. In his case, as a result of a tumour, 'a large component of the right frontal cortices was not functionally viable.' No longer able to intuit the value or emotional meaning of life situations, he was reduced to trying to compute rationally, as from first principles, in every case, and his life became insupportable. Not only did he take for ever to decide what to think or to do, but he reached, for an intelligent man, some very foolish conclusions. And it is one of the messages of this book that imagination is not an impediment, but, on the contrary, a necessity for true knowledge of the world, for true understanding, and for that neglected goal of human life, wisdom. (The Matter with Things, vol. 1, p. 549)

It is humbling to think about how truly limited we would be in our ability to ascertain the truth without our emotions. But do we really expect any differently? Human beings are not simply calculating machines, but breathing and feeling embodied organisms.

Sadly, many Christians have, I fear, inherited the Enlightenment bias against the emotions. One verse that I often hear cited to dismiss the use of emotions as a way of discerning the truth is Jeremiah 17:9:

The heart is deceitful above all things, and desperately sick; who can understand it?

In the view of some, this verse basically means that, unlike our pristine minds, our hearts cannot be trusted. You should never, in the words of the popular saying, "follow your heart."

However, I do not think this verse means what many people think it means.

For one thing, the Hebrew root לֵב (lēḇ; pronounced "lave"), encompasses a wide range of meanings, not all of them identical with the Enlightenment understanding of the heart as emotional rather than rational. (The word הַלֵּ֛ב which is here translated as "the heart" is the root לֵב prefixed by the definite article הַ.)

As summarized in the Oxford Brown-Driver-Briggs Hebrew lexicon, the לֵב root instead refers more holistically to the "inner man, mind, will, heart" (BDB, s.v. לֵב). This is the same root found in the shema of Deuteronomy 6, for instance, which calls on the people of Israel to love the Lord with all their heart, soul, and strength – in other words, with their entire being.

In contrast to a modern Western understanding, for the Hebrews (and, as we shall soon see, the Greeks as well), the "heart" is often associated in the prophets with the idea of "study," "thinking," and "reflection" (3.c), and in wisdom literature such as Proverbs and Ecclesiastes, with "knowledge," the "wise mind," and the "intelligent mind" (3.b). This is quite different to the way some Christians read Jeremiah 17:9, wherein they try to contrast the heart with the mind. In the Hebrew this is simply not a clear distinction.

All of this is to say that we have to be careful not to let the meaning of "heart" that is operative in our modern culture control our reading of an ancient text like Jeremiah 17:9. We should not assume that the ancient author(s), who lived in a starkly different culture with differing views of the human person, had exactly the same meaning in mind as we do when when they used a word like הַלֵּ֛ב.

Ancient Greek translations of Jeremiah 17:9 are also helpful to look at because they reveal how Hellenized Jews living closer to the time of Christ understood the Hebrew text. In the Ralphs edition of the Septuagint, the verse reads like this:

The heart is deep beyond all things, even as a human is; and who will come to understand it?

The first thing to notice is that the description in Greek is not "deceitful" as in the Hebrew, but rather "deep" (βαθύς; "profound; at the extreme of"). This offers an important insight into the way these Jewish translators interpreted the Hebrew.

Secondly, it should be noted that "heart" here is simply my translation of the Greek καρδία (kardia), which, again, does not have an exact one-to-one correspondence with our modern understandings of "heart." For the Greeks, the καρδία was "[the] seat of physical, spiritual, and mental life" (BDAG, s.v. καρδία, 1.). This is again a much more holistic view than the Enlightenment understanding which separates the heart and the mind.

If the Hebrews and Greeks believed we think with our hearts, then contrasting the "heart" in Jeremiah 17:9 with the mind is a non-starter.

All of this challenges the popular apologists who, seeking to "win the culture wars," blithely tell you not to "follow your heart." The reality is that, even in Scripture, the human person is much more complex and profound than they let on.

As McGilchrist suggests, humans require both our reason and our emotions for a true understanding of the world; without either, we would go radically astray. Emphasizing reason over emotion – separating the "mind" from the "heart" – is not possible, helpful, or biblical.

Perhaps this is why in Peter Jackson's Lord of the Rings, Aragorn asks Gandalf, his friend who has reached the limits of rationality, "What does your heart tell you?" To which Gandalf responds, "That Frodo is alive."

And you know what? Gandalf's heart was right.

Just some food for thought.