The Nature of Fire

Mr. Minderhoud is a teacher in Covenant Christian High School and a member of Hope Protestant Reformed Church, Grand Rapids, Michigan.

Have you ever sat by the cozy warmth of a flickering campfire, staring at and contemplating the bright flames? Or have you ever witnessed the raging flames of a much larger fire, perhaps one that is burning uncontrollably, and felt its intense heat? In either case there is something about the mysterious nature of fire that intrigues us and makes us pause. We either contemplate its warmth and beauty or marvel at the speed and strength of its devouring destruction. Fire inspires an array of feelings within us, for it has a number of fascinating characteristics, from its heat and brightness to its insatiable appetite and destructive power. Furthermore, the Lord often uses fire in the Scriptures as a simple picture to us of profound spiritual realities. We do well, therefore, to consider what God teaches us through the gift of fire.

What is Fire? 

Children learn in school and we recognize from experience that a fire requires three things: a fuel source, a supply of oxygen, and a means of ignition. The fuel source, in most day-to-day cases, is a material made of carbon compounds. For example, wood products, which are a common source of fuel, are made of the carbon compound cellulose. Cellulose is a polymer (a long chain of hundreds of the same particular molecule) of the molecule C6H10O5 —a substance derived from the glucose molecule. Secondly, these carbon compounds must combine with the oxygen in the air to make a fire. Chemists call this combustion—the reaction of the fuel with oxygen, producing carbon dioxide gas, water vapor, and energy (either in the form of heat or light). Finally, there is a third important requirement for a fire. You can place all the wood you want in a pile and surround it with oxygen, but a fire will not start. This is a good thing, because oxygen surrounds us, as well as the many combustible substances in the creation, and yet, these things do not spontaneously start on fire. In order for a fire to start, there must also be an ignition source. The ignition source is some form of heat, produced either from friction, a strike of lightning, light focused by a mirror or magnifying lens, or from some other source of energy. For a fire actually to start, a series of interesting events must occur. First of all, the fuel source must be heated by an ignition source. This heating causes some of the particles of the fuel to break away from the rest of the fuel particles and to rise as a gas. These escaping gases are a part of what we commonly recognize as smoke. Smoke contains tiny, airborne, solid particles (usually some carbon atoms that we call soot) that make smoke visible to us. But smoke also contains flammable gases that come out of the fuel when it is heated. As these flammable gas particles get hot enough, a chemical reaction occurs between them and the oxygen gas molecules of the air. At that point, the molecules of these gases break apart into various atoms, which combine with oxygen gas and reorganize to form new products. Most commonly these new products are carbon dioxide and water vapor. In addition to the production of carbon dioxide and water vapor, there is also the release of more heat energy. This new heat energy is used to further evaporate more molecules of the fuel. These vaporized molecules will, in turn, chemically react with more oxygen to make more carbon dioxide, water, and heat. Thus, a fire, once started, is self-propagating. (Notice that the particles from the fuel source must reach a particular temperature in order to combust. This temperature is called the "ignition temperature," and is unique to every substance. Therefore it is not necessary to have a flame start a fire, but merely the correct temperature. For example, a building that is engulfed in flames can produce such heat that although the flames never touch any of the surrounding buildings, these buildings can and will spontaneously ignite if a portion of the building reaches its ignition temperature). 

In addition, when wood burns, the actual wood does not burn, per se, but it is the vapors from the wood that burn. When the vapors leave the wood, the left-over non-combustible materials, such as calcium and potassium, remain as ash. The other main left-over material is pure carbon, or "char," which can burn but does so much more slowly than the gas particles from the fuel. This char is what is used in one's "charcoal" briquettes. Since char has little of the gaseous substances combined with it, the char can burn without making much smoke (gas particles) and burns in a very slow but even way—perfect for cooking one's supper. 

Once a fuel begins burning, the tiny particles in the smoke begin to glow as a result of the heat given off from the combustion process. These glowing particles emit light and are called the flame. The flame flickers and can have different colors. The flickering of the flame has to do with the movement of air around the fire. Hot air rises and cooler air rushes into the area of the flame to replace the rising hot air. These convection currents are responsible for the movement of the flame. The color of the flame has to do with the temperature and type of material that is burning. As some of the particles of burning fuel rise in the smoke they begin to glow because they are so hot. 

Different molecules and different atoms of material will glow a different color when heated. For example, most wood products will produce a characteristic yellow/orange flame. But perhaps you have had certain metals in the fire with the wood. Then you may have seen bursts of green or red in the flame. Certain metals, like copper, produce green or blue flames. Strontium compounds produce a bright red flame, while potassium compounds produce violet flames. These kinds of compounds are responsible for the colors in firework displays. In addition, the different colors of a flame are related to the different temperatures of the flame. The "coolest" part of a flame emits a yellow color, while "hotter" flames emit a blue color. 

From these properties and others, it is abundantly clear that there is much more to a fire than what first meets the eye. What makes us pause at the sights and sounds of fire is its complicated and mysterious nature. Fire is a phenomenon so common in our daily lives and yet hardly understood. We only scratch the surface of its unique workings. Although science often boasts of its findings and knowledge of the creation, in reality it knows very little of the inner workings of God's creation. When we consider such complexity in such an ordinary and important aspect of creation, our finiteness is accentuated. 

Fire is certainly a special gift of God to man. It is as useful as it can be destructive, and its great importance in our day-to-day lives is so extensive that we cannot imagine life without it. From the internal combustion engine to forest fires, fire is a "creature" of God that is necessary for man's physical existence and for the benefit of the entire creation. It is of no surprise that the "ancients" considered fire to be one of the four basic "elements" of the creation. 

Typical Fire 

As Christians, we look at God's gifts with the "spectacles of Scripture" in order to see what spiritual truths God reveals to us about Himself. We confess that God reveals His power and divinity by use of the physical creation. Fire is no exception. It too is one of the "many characters leading us to contemplate the invisible things of God" (Belgic Confession, Art. 2). 

Many of Scripture's references to fire are used to describe God's fiery judgment upon the wicked (cf.Psalm 21Psalm 68). The complete destruction of the wicked is pictured by the destructive nature of fire. Think of the charred remains, for example, of a forest that once was lively and beautiful. Consider the white and black ash remains of a simple campfire—solid logs reduced to windblown ashes only a short time later. So it is with the reprobate. "Therefore as the fire devoureth the stubble, and the flame consumeth the chaff, so their root shall be as rottenness, and their blossom shall go up as dust: because they have cast away the law of the Lord of hosts, and despised the word of the Holy One of Israel" (Is. 5:24). 

In a previous article ("Tried by Fire," Standard Bearer, vol. 78, no. 14), we considered how fire pictures the purifying work of the Holy Spirit in our lives. The Old Testament pointed to this with references to the "refiner's furnace" (Mal. 3:1-6). The New Testament teaches this, as in Matthew 3:11, "I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost and with fire." Think also of the signs accompanying the outpouring of the Holy Spirit upon the church, for "cloven tongues like as of fire...sat upon each of them" (Acts 2:3). The fire referred to in these passages points to the purifying work of the Holy Spirit, by which the Spirit cleanses us from the filth of our sins and gives us a new and holy life. 

In addition to the above, the Scriptures speak of fire in regard to other aspects of our lives, particularly in regard to sins of the tongue. It is that to which we now focus our attention. James 3:6 speaks of the tongue as a fire, an all-consuming iniquity, that defiles the whole body and sets on fire the course of nature. For, as we read in Matthew 15:11, it is that which cometh out of a man—that which he speaks—that defiles a man. Sometimes what comes out of our mouths is not uplifting words but words that tear down, bringing only strife and confusion. Such is the havoc wrought by a flaming fire. The tongue, as a fire, can be a source of great sorrow and strife in the church of Jesus Christ. 

As brothers and sisters in the body of Christ we are thankful to God for the blessed fellowship and communion we enjoy one with another, a blessed organism united in Christ our Head. How devastating, then, is the fire of strife and contention when it burns among us. Consider the swift and sudden destruction of a house fire. How quickly it can all go down—a beautiful home reduced to rubble and charred remains in a matter of minutes. Strife and contention are fed by the spread of idle tales and gossip, backbiting, and slander. What we speak—orally or with the use of technology—can become a destructive fire spreading and burning uncontrollably, leaving nothing but charred remains in its path and doing great damage to the organism of the body of believers. 

A fire never says, "It is enough" (Prov. 30:15, 16). When fed by fuel it burns on and on, wreaking havoc and destruction. In order for strife to cease we must not repeat everything we hear. We must keep our mouths closed if what we have to say, "tweet," blog, or post on Facebook is not meant to edify and build up the people of God. For "where no wood is, there the fire goeth out: so where there is no talebearer, the strife ceaseth. As coals are to burning coals, and wood to fire; so is a contentious man to kindle strife" (Prov. 26:20-21). If left unchecked, idle tales spread rapidly from tongue totongue. Oh how great a matter a little fire kindleth. 

May our lips be characterized by the "balm of Gilead" (Jer. 8:22), not the burning fire of evil. The instruction is so simple, and the picture so clear—preventing contention is as simple as keeping our mouths closed; no fuel, no fire—and yet, how difficult, yes, impossible, except it be for the grace of God. For the tongue noman can tame. How thankful we are, therefore, for the work of the Holy Spirit within us. May we grow in the guarding of our tongues and pray that the Lord keep the door of our lips (Ps. 141:3). 

How thankful we are to God for the good gift of fire! It certainly helps us in our day-to-day physical lives by providing necessary heat, combustion for our engines, and a means to destroy and purge unwanted materials. But more importantly, it serves to teach us many spiritual truths. As a fascinating creature of God, fire gives us good opportunity to meditate upon our sovereign Creator and His mighty works. By God's grace, we are prompted to pause and contemplate the purifying work of the Spirit in our lives—especially that very necessary work of taming our fiery tongues.