Back in the mid-1980s, while working as a resident field engineer for the City of San Diego, I was overseeing a project that required the contractor to locate a buried cable beneath a city street. Instead of using the usual electromagnetic locator that induces a detectable current in the wire, he called in a dowser carrying two parallel brass rods. As I watched, he slowly walked over the suspected area. Suddenly the rods swung inward toward each other. He marked the spot, the crew dug down, and there lay the cable.

As an engineer, I was trained to trust observation before explanation. I had observed something I could not explain. I was skeptical. Afterward, I asked if I could try.

Holding the rods exactly as he had, I slowly walked over the same ground. Nothing happened. I remember feeling two emotions at once: surprise that the rods had worked for him and annoyance that they did nothing for me. He smiled and admitted that his own first attempts had also failed. That did little to soothe my bruised ego.

I hadn’t thought much about that incident for nearly 40 years until I recently read about a 79-year-old professional dowser who reportedly has an impressive record locating underground water. He not only identifies where to drill but also estimates the depth and expected water flow. Contractors reportedly continue to hire him, convinced that his success justifies the expense. Many scientists explain such success as subconscious interpretation of landscape clues — subtle changes in vegetation, drainage, or topography. That may account for some cases.

But what about reports of locating human remains or other buried objects where no obvious surface clues exist? Those accounts are more difficult to explain by the usual theories.

The mystery is hardly new. For more than three centuries, dowsing has stood at the uneasy intersection of science, faith, and human experience. Scientists, physicians, engineers, philosophers, and theologians have all attempted to explain it, yet no single explanation has gained universal acceptance. Some have dismissed it as fraud. Others have attributed the movement of the rods to ideomotor effect: the unconscious movement of tiny muscles without the user’s awareness. Still others have proposed that some cases may reflect a natural human ability that science has not yet adequately explained.

The Catholic world has wrestled with the question no less seriously. The issue was never simply whether dowsing appeared to work, but whether its source was natural, psychological, or preternatural.

During the seventeenth century, Jesuit scholar Athanasius Kircher explored magnetism and other natural forces in an effort to determine whether dowsing might have a physical explanation. In France, Abbé Pierre Le Lorrain de Vallemont defended water and mineral dowsing as a natural phenomenon, while Father Pierre Le Brun argued that many demonstrations were better explained by deception or demonic influence. Father Claude-François Menestrier joined the debate by criticizing attempts to reduce the phenomenon to simple natural causes, and Jesuit mathematician Father Kaspar Schott suggested that unconscious muscular movements might explain much of what observers witnessed — an idea strikingly similar to today’s ideomotor theory.

The controversy intensified after the Jacques Aymar affair of 1692. When Aymar claimed to use a dowsing rod to pursue thieves and murderers, physicians, university scholars, civil authorities, and churchmen throughout France entered the debate. The question had grown far beyond finding water. It now touched the limits of human knowledge and the possibility of spiritual deception.

The discussion never entirely disappeared. In the twentieth century, Abbé Alexis Bouly sought to rescue dowsing from its occult reputation by coining the term radiesthesia and encouraging its investigation as an empirical phenomenon. His contemporary, Abbé Alexis Mermet, became internationally known for using rods in searches for water, minerals, and other hidden objects. Yet even as interest grew, Church authorities continued to warn that using such practices for divination, fortune-telling, communication with spirits, or attempts to obtain hidden knowledge through preternatural means crossed a moral boundary.

Scripture repeatedly warns against divination and attempts to obtain hidden knowledge through occult means. Those warnings should not be taken lightly. The question, however, is whether every use of a dowsing rod necessarily falls into that category. If a dowser merely uncovers an underground water vein through some poorly understood natural process, the moral question differs substantially from his attempting to predict the future, communicate with spirits, or seek forbidden knowledge. Distinguishing between those possibilities has occupied theologians for centuries.

That historical tension is what fascinates me most. Had evidence been overwhelmingly persuasive, the debate would likely have ended centuries ago. Had the phenomenon been nothing more than obvious fraud, serious investigators would have abandoned it. Instead, thoughtful people have continued to examine it while reaching remarkably different conclusions.

My own experience settles nothing. I never successfully used dowsing rods. Yet I am reluctant to dismiss every account as foolishness or to conclude that every unexplained success is necessarily demonic.

History counsels humility. For more than three centuries, scientists, engineers, physicians, priests, and skeptics alike have examined this phenomenon without reaching complete agreement. That alone should encourage intellectual modesty.

Whether dowsing ultimately proves to be unconscious muscular response, an uncommon natural ability, an innate capacity that requires practice, simple coincidence, deliberate deception, or something spiritually dangerous will continue to be debated. Until we know more, prudence requires both intellectual honesty and spiritual discernment. That is why I caution against both gullibility and reflexive dismissal. Some claims undoubtedly prove false. Others may eventually receive ordinary scientific explanations. A few may continue to resist easy answers.

Not every unexplained phenomenon is fraudulent. Not every unexplained phenomenon is demonic. And not every unexplained phenomenon is the work of God.