The spiritual writers of the Low Countries of the late Middles Ages are famous for their delicate sense of balance, particularly in contrast with some of the questionable writings that were circulated elsewhere in Europe at that time. Among the gems of the mediaeval Benelux, Blessed John of Ruusbroec has a special place in my heart. One reason for this is that I think he’s taken good care of me personally. Another is that he’s beloved by another of my favourites, Saint Titus Brandsma. But a third reason is that his doctrine has points that strike me as having come from a pen with incredible observation and foresight, not to mention that Flemish sense of harmony.

Ruusbroec, like Teresa of Avila and John of the Cross (and thus the entire Discalced Carmelite tradition), on whom he seems to have had either a direct or indirect influence, is a teacher of “both/and,” not “either/or.” He holds in tension the dimensions of action and contemplation in the life of the contemplative. This is part of his sense of balance. Whatever page of his you turn to, you won’t find any contradiction of the (later) reformed Carmelites’ idea that contemplation exists for the sake of good works. Ruusbroec is very conscious of this. He’s reacting to contemporaries like Eckhart and a movement gaining traction in the Low Countries called “the Free Spirits.”

Now, the way that Ruusbroec goes about this is for me very interesting. Most spiritual literature of the Middle Ages and Modern period tends to envisage our life in Christ according to various states (e.g., purgative, illuminative, unitive ways; action, contemplation) and the transitions between those states. Ruusbroec, with a sensibility more at home in East and Southeast Asia (e.g., Marcel Văn and his refrain of “changing suffering into joy”), thinks of processes. He thinks about well-demarcated states and transitions, too. He’s a child of his time and culture. But he has, in addition, a remarkable penchant for processes.

That’s how he in particular holds different polarities in tension, such as that between action and contemplation.

One of his metaphors is, to me, utterly remarkable. Consider this passage, where Ruusbreoc describes the action of boiling water and compares the motion of the water, which is part of a single process under the infusion of heat, to the single process of the Spirit infusing divine love in us:

Boiling water. Consider now a comparison which will show what this exercise is like. When natural fire has, by means of its heat and its power, brought water or some other liquid to a boil, that is its highest activity. The water then reverses direction and falls back down to the bottom. where it is again raised up to the same boiling activity through the power of the fire, in such a way that the fire is constantly exerting its force and the water is constantly boiling. The interior fire of the Holy Spirit works in the same way. It drives, urges, and impels the heart and all the powers of the soul up to the boiling point, that is, up to the giving of thanks and praise to God in the way I have already described. Then a person falls back down to the same ground where the Spirit of God is aflame, so that the fire of love is constantly burning and a person’s heart is constantly thanking and praising in word and deed and yet constantly remaining in humble lowliness, for such a person considers what he should do and would like to do to be something great and what he actually does to be something small.[1]

Like water that rises to the top when heated, we ascend from the fire of prayer. Then, like water that moves about and in contact with the rest of the world cools, we descend again to find the source of our heat. The rate at which this happens is incredibly variable. For some bits of water in the pot, it’s very fast. For others in the same pot, it’s slower. As less heat is applied, the speed and the length of the trajectory of the water change. As more heat is applied, they change again. In fact, if you apply enough heat, the movement of the water becomes rough and turbulent.

Overall, this image is illustrative of one of Ruusbreoc’s lapidary phrases in another work: “Anyone who does not possess both rest and activity in one and the same exercise has not attained this righteousness.”[2] But the image goes a lot farther.

The image of the boiling water is completely in my wheelhouse. At the graduate level, one of my specializations is actually in what chemists, physicists, and engineers call “non-equilibrium thermodynamics.” Basically, it means I know a lot about Ruusbroec’s example. And I’ll say, he’s smart. He uses the metaphor exceptionally well.

For me, Ruusbroec has understood his image astutely. Of course, he doesn’t understand that the bits of water rise because hot things have a lower density, and thus they rise to the top under gravity, then their density lowers when they cool in contact with the air, and so they fall down again to the heated surface below. He’s probably not aware that you don’t need water. With the right temperature gradient, any liquid will do. And he doesn’t seem to be aware that you don’t even need to make the water boil. Boiling is turbulent and locally unpredictable, and you can actually create pre-turbulent regimes where the convection of the liquid happens regularly and in vaguely honeycomb-like cells. The latter are called Bénard cells, and they’re really pretty. This is someone else’s video of them:

But getting back to Ruusbroec—he knows what he’s talking about. The guy is observant and clever. The whole point to Bénard cells is that they are a regime that is “out of equilibrium” because you push some energy across it. It’s not at equilibrium. Things at equilibrium are boring. They’re always dead. The perfect equilibrium is a stone, a crystal, anything that doesn’t change.

If you have something a little bit out of equilibrium, you can increase the energy flow across the system. You can turn up the heat in the case of the water in a pot, and you’ll move the water even farther from its equilibrium state. Eventually, with a big enough energy push, it gets all bubbly and turbulent, and all of a sudden you can’t predict what’s going to happen with one bit of the water at any given time.

So, translated into modern vocabulary, what Ruusbroec is saying is that the Christian life is like throwing energy across the water. The Spirit pumps grace across our psychosomatic dynamism. And it’s supernaturally alive! It’s not just a bunch of nouns that we can describe to the names of the virtues, the names of our acts, and the descriptions of our psychological abilities. Something energetic is charging through us. And that moves us away from equilibrium. It dislodges us from a static, steady state. It pushes us outside of ourselves left to ourselves. It moves us closer to the inherent unpredictability of life.

Am I reading too much into this? Perhaps. But that Ruusbroec seems to have some intuition about “non-equilibrium” is hard for me to deny, because the very next paragraph gives a second simile. This one also leaps off the page to me as an example of “non-equilibrium”:

The sun in late springtime. When summer draws near and the sun rises higher in the sky, it draws moisture out of the earth through the roots and trunk of a tree into its branches, and as a result leaves, blossoms, and fruit appear. In the same way, when Christ, the eternal sun, rises higher in our hearts and it becomes summer in the rich flowering of virtues, then he sheds his light and heat onto our desires so as to draw the heart from the multiplicity of earthly things to unity and interior fervor. He makes the heart grow and bring forth the leaves of fervent affection, the blossoms of a devotion that is full of desire, and the fruit of thanksgiving and praise, and he preserves this fruit eternally in the humble pain that arises from our constant awareness of our deficiencies.[3]

Ask a specialist in non-equilibrium thermodynamics what the sun is, and they’ll tell you it’s a source of radiative heat flow that maintains our entire planet out of equilibrium. So Ruusbroec is essentially repeating the same trick. Describe a flow of energy. Apply it to a well-chosen system. Describe the evolution of the system with such an energy flow across it. Things become more life-like. In this case, we don’t just get the initially regular Bénard cells and then the turbulent boiling of a liquid. Rather, we get actual life itself—leaves, blossoms, fruit.

Since I’ve first read these two back-to-back paragraphs in Ruusbroec’s masterpiece The Spiritual Espousals, I’ve been amazed. He understands a very fine point that many spiritual writers seem to brush over by using examples that are less clear and focused. His images strike to the heart of the matter, at least as a modern scientist would understand the heart of the matter.

Grace has to be treated like a living thing. And for that, the absolutely best images will be ones that highlight the very conditions of life itself. Ruusbroec is completely right that a flow of energy, a continual infusion of energy through and across a system whose boundaries aren’t broken, is one of the indispensable conditions. There has to be an outside factor that remains outside and pushes some energy across an inward space that retains its boundaries. Without it, no life! At least not for us humans, us material creatures.

To be sure, other images of the spiritual life are important, too. I would never give up my beloved image of the wood that becomes the flame (e.g., John of the Cross’ Living Flame of Love). We have to be something, too. We have to speak about what we are. God transforms us. That matters.

But all that, in the end, is pointless if we’re not able to seize and be seized by the idea that what we become is alive. And one condition of life is that it is not a mere state, not at equilibrium. It requires a constant flow across it—in the supernatural life, a flow of graces and gifts. And when pushed far enough away from its steady state of being merely human, this supernatural life becomes locally unpredictable like the turbulence of boiling water, for the more we are docile to the gifts of the Holy Spirit—which are, to borrow a couple of Ruusbroec-isms, “a life of love at the highest level of its activity, above reason and understanding,” “above reason, though not without reason”[4]—the more will individual events pass outside human prediction, calculation, and precision. We know overall what is happening. The water is boiling. Something is alive. This is the life of grace. But each little movement becomes less consciously determined and analyzable. It exists more because of the divine infusion and flow of graces and gifts, accepted with docility, and less because of our deliberately, laboriously controlled application of the virtues. That’s life, and the Lord came that we might have it abundantly.

[1] John Ruusbroec, Spiritual Espousals II.2/3.A, in The Spiritual Espousals and Other Works, trans James A. Wiseman (Mahwah, NJ: Paulist Press, 1985), 81.

[2] Spiritual Espousals 2.4.C, in ibid. 135.

[3] Spiritual Espousals II.2/3.A, in ibid., 81.

[4] Spiritual Espousals II.2/3.C, II.4.B, in ibid., 115, 112, 131.