On the magnet, magnetick bodies also, and on the great magnet the earth: a new physiology, demonstrated by many arguments & experiments

In Short

This foundational treatise on experimental physics systematically investigates the natural properties of loadstones, iron, and electrical substances. It sets out to dismantle centuries of inherited folklore and speculative philosophy through meticulous hands-on experimentation. By examining magnetic attraction, polarity, and variations in needle movement, the work establishes that the terrestrial globe itself functions as a colossal magnet. Its enduring legacy stems from its revolutionary insistence on direct observation and repeatable empirical proof, which effectively laid the groundwork for modern physical science and transformed humanity's understanding of planetary forces.

The Story

The work opens with a severe critique of ancient naturalists and medieval scholars who relied on unverified fables, unreasoning opinions, and speculative guesswork. Rather than accepting traditional tales about magical mountains or mineral antipathies, the text insists that truth must be mined directly from the earth through manual labor and demonstrable argument. It begins by examining the physical origins of the loadstone, tracing its nomenclature, its regional varieties, and its natural co-existence alongside iron ore within the earth’s crust.

Moving beyond mere descriptions of minerals, the text introduces a vital distinction between electrical attraction and magnetic behavior. While rubbed amber or glass attracts lightweight objects through temporary, superficial effluvia, magnetic bodies act through an innate primary vigor that penetrates to the very center of iron. The text forcefully rejects the traditional concept of passive attraction, renaming the phenomenon coition to describe a mutual running together driven by an internal form.

Through hundreds of practical demonstrations, the inquiry traces how magnetic forces pass unimpeded through dense materials like wood, water, and marble, yet are uniquely diverted by plates of iron. It details how iron rods acquire verticity—a definite polar direction—either through contact with a loadstone or simply by being forged and cooled while aligned with the earth's axis. Extreme heat, represented by the untamed tyrant of fire, is shown to strip iron of its acquired polar strength, whereas simple mechanical friction awakens latent magnetic potential.

The narrative expands from small laboratory instruments to global geography, addressing the practical challenges faced by mariners. It systematically addresses the variation of the compass needle from true geographic north, explaining that these deviations are caused by the uneven distribution of elevated landmasses and ocean basins across the globe, rather than by distant celestial stars. The text then introduces the phenomenon of magnetic declination or dip, demonstrating through spherical loadstones—terrellas—how magnetized needles tilt downward at predictable angles depending on their latitude between the equator and the poles.

In its final movement, the work synthesizes these empirical findings into a unified cosmological framework. The earth is revealed not as an inert mathematical construct, but as a living, dynamic body governed by an internal magnetic potency. By proving that spherical magnetic bodies possess innate rotational forces, the text dismantles traditional Aristotelian objections against planetary motion. It concludes by arguing that the earth's daily rotation about its poles arises naturally from its own primary magnetic vigor, securing the planet's place within a dynamic physical universe.

How It Unfolds

Scrutinizing the ancient fables The inquiry opens by contrasting traditional speculative philosophy with direct experimental evidence, rejecting long-held myths regarding magnetic attraction and mineral origins.

Distinguishing electricks from magneticks The text establishes a fundamental boundary between electrical friction, which operates through superficial effluvia, and true magnetic coition, which acts through an innate primary force.

Tracing the kinship of iron and loadstone Demonstrations reveal that raw iron ore and refined loadstones share a single underlying essence, with both acquiring and retaining polar properties under identical conditions.

Testing the limits of magnetic force Experiments prove that magnetic influence penetrates solid barriers such as wood and stone, while iron plates divert the invisible orb of virtue.

Exposing iron to the fire The text shows how intense heat destroys acquired verticity, while mechanical friction and proper alignment with the earth can awaken latent magnetic strength.

Explaining maritime compass variation The narrative examines why compass needles deviate from true north, attributing these variations to the irregular mass of continental landforms rather than heavenly influences.

Mapping the magnetic dip Using small spherical loadstones called terrellas, the text illustrates how magnetized needles tilt at varying angles according to their regional latitude.

Declaring the earth a giant magnet The work culminates by demonstrating that all terrestrial magnetic phenomena reflect the natural, primary vigor of the earth itself, supporting the concept of planetary rotation.

The People

The Experimental Investigator The central driving voice of the text, dedicated to uncovering the hidden causes of natural phenomena through manual labor, meticulous measurement, and physical demonstration. Impatient with unreasoning men and speculative academic traditions, this figure seeks to reveal the secret properties of the terrestrial globe by pointing them out directly to the senses.

The Ancient and Medieval Philosophers A collective group of historic authorities—including Pliny, Galen, Aristotle, and Albertus Magnus—whose written accounts dominated early natural philosophy. Within the text, they represent the reliance on secondhand reports, unverified fables, and theoretical speculation, serving as a foil against which the necessity of modern experimental proof is demonstrated.

The Mariners and Metallurgists Practical tradesmen, navigators, and mine workers whose everyday observations provide raw material for scientific analysis. Though often lacking theoretical training, their real-world encounters with iron ores, compass variations, and sea routes offer genuine physical facts that the text organizes into a coherent scientific doctrine.

Giambattista della Porta A prominent contemporary natural philosopher specifically singled out for criticism. He represents educated authors who conduct flawed experiments—such as claiming diamonds impart magnetic polarity to steel—thereby propagating new errors by failing to account for the earth's background magnetic influence.

In Its Own Voice

"Clearer proofs, in the discovery of secrets, and in the investigation of the hidden causes of things, being afforded by trustworthy experiments and by demonstrated arguments, than by the probable guesses and opinions of the ordinary professors of philosophy..."

The text introduces its core methodology, placing physical demonstration above abstract academic speculation.

"There is a magnetick nature peculiar to the earth and implanted in all its truer parts in a primary and astonishing manner..."

The fundamental premise of the work is declared, identifying the earth itself as the ultimate source of magnetic behavior.

"Let an experiment then be made in fire, that untamed tyrant of nature."

The author describes the rigorous physical tests used to analyze how heat alters acquired polarity in iron.

What It's Really About

At its core, the text is a manifesto for the empirical scientific method, arguing that physical truth can only be discovered by touching, measuring, and testing the material world. It seeks to overthrow centuries of reliance on scholastic authority, replacing literary tradition with physical evidence that can be perceived by the human senses.

Beyond its methodology, the work presents a unified physical theory of the planet. It argues that magnetism is not a rare property confined to isolated mineral specimens, but the fundamental organizational force of the entire terrestrial globe. By showing that magnetic forces govern both microscopic needles and global orientations, the text connects small-scale laboratory physics directly to planetary motion and cosmic structure.

Why Read It Today

This work offers a vivid window into the dawn of modern experimental science. Readers interested in the history of ideas will appreciate watching an early researcher dismantle ancient myths—such as garlic disabling loadstones or diamonds attracting iron—through clear, repeatable trials. The prose carries a confident, energetic tone that treats laboratory work as a grand adventure into unknown territory.

The primary difficulty for contemporary readers lies in the historical style and terminology. The text frequently engages in long-winded arguments against forgotten 16th-century writers, cites extensive lists of classical authors, and uses obsolete physical concepts like "verticity," "coition," and "effluvia." Modern readers must also navigate long sentences packed with Latinate phrasing and technical metallurgical descriptions.

What remains unforgettable is the sheer delight of direct discovery. Watching the author float iron wires on corks, heat needles until red-hot, and move compasses around spherical magnets conveys the authentic thrill of early scientific breakthroughs. It stands as an enduring monument to human curiosity and the power of experimental proof.