Different but Equal

It’s not uncommon to read, on a snack package, the phrase “with chocolate taste,” often printed in bold uppercase. The wording plays a subtle trick on the mind. Most people assume the product must contain chocolate. Yet a flavor is not a substance. More often than not, what we bite into carries only the impression—an illusion—of chocolate.

The same applies to color. Our brain is just as easily misled. Colors behave like flavors: they may smell—pardon… look—like a particular hue, but they are subjective sensations rather than fixed properties of the outside world. They shift with context, changing according to their surroundings. More striking still, identical colors can appear different under certain conditions, while different colors may look the same. This phenomenon is known as color induction.

Even texture plays a role. It can alter how we perceive a color’s intensity and tone. Take beer and an egg yolk: they may share the same orange hue and gradation. Yet the brain reads them differently. The glass and the liquid are perceived as translucent, so their color seems lighter, duller, more diluted. The yolk, by contrast, appears opaque, with a richer, more glossy, more solid color.

In this picture, the beer and the egg share exactly the same orange gradation.

How a Human Bone Inspired the Eiffel Tower

Few people know that the human femur—the body’s largest and strongest bone—played an indirect role in the thinking behind the design of the Eiffel Tower.

Part of the tower’s structural logic can be traced to Swiss engineer Maurice Koechlin, chief engineer in the firm of Gustave Eiffel. While determining how forces would travel through the iron frame, Koechlin applied a principle that places material along the natural paths of tension and compression.

A comparable pattern had been described earlier by Zurich anatomist Hermann von Meyer. His research revealed that the femur’s internal structure forms a network of delicate struts known as “trabeculae.” These tiny elements follow the directions of mechanical stress inside the bone, creating a highly efficient system of support—even though the femoral head sits off-center from the shaft.

The mathematician Karl Culmann later showed that these trabecular patterns correspond closely to the principal stress lines calculated in engineering. His method, called graphic statics, provided a visual way to map how forces move through structures.

This link between anatomy and engineering influenced nineteenth-century structural thinking. The same principle—placing material only where forces demand it—guided the development of lighter, more efficient frameworks in bridges, cranes, and reinforced-concrete designs.

Beyond Constructible Forms: The Undecidable Bars

In 1934, the Swedish artist Oscar Reutersvärd sketched a peculiar triangle made of small cubes, neatly aligned on an isometric grid. Everything looked geometrically sound—until the mind tried to assemble it in real space.

Soon after, Lionel Penrose and Roger Penrose published their famous Penrose Triangle—three beams joined by apparently right-angled joints—and M. C. Escher explored similar paradoxes in works such as Waterfall and Ascending and Descending.

This triangular paradox has distant echoes in ancient Greek geometry, but Reutersvärd gave it a clear visual form: the impossible figure.

That’s the charm of impossible figures: every part looks right, yet the whole quietly breaks reality.

I began exploring these paradoxical structures in the 1980s. My interest grew naturally from the meeting point of two inclinations: a mathematical curiosity about spatial logic and a visual fascination with form. Over time I produced many variations—sometimes rediscovering ideas that others had already touched upon, occasionally arriving at configurations that felt genuinely new. In geometry, complete novelty is rare; most discoveries emerge as unexpected turns within an existing landscape.

One example from that period is the study shown here, created in the late 1990s and titled Undecidable Bars.

© Gianni A. Sarcone, 1997-2001

Parallel bars appear to run calmly side by side, yet their connections quietly sabotage the logic of space. Perspective slips from one segment to another, forcing the eye to accept incompatible viewpoints at the same time.

Each element seems perfectly normal.
Together, they form a structure that cannot exist.

Some bars appear to pass through others; some join where no joint should be possible. The geometry behaves as if the object were bending through space, while every line still respects the conventions of perspective drawing.

The result is an undecidable figure—a form the eye can follow effortlessly, but the mind cannot reconstruct.

Available as fine art print from my online gallery.

Over the years I have created hundreds of images built on similar principles, across different formats and media. If these works interest you for a book, exhibition, or monograph, feel free to contact me.

IF: The Two-State Threshold

I’ve always been drawn to impossible objects—those forms that slip between logic and illusion, never fully settling into one or the other.

This piece grew out of an old idea I felt compelled to revisit, almost as if reopening a long-forgotten door. A binary door, in fact—one that leads to two distinct worlds. Depending on how you look at it, it shifts, tilts, and reveals something else.

It starts with pencil on paper. A loose, intuitive phase where the form finds its way. From there, I move into FreeHand MS—an old tool I’ve never quite let go of. It still gives me a certain precision and feel I can’t replace. Finally, I refine the piece in Photoshop, adjusting, balancing, pushing it toward that delicate point where everything holds together.

There’s still work to be done. Something remains unresolved—but maybe that tension is part of what keeps it alive.

Master of Numbers

The Master of Numbers” is an Op Art photomosaic portrait of the renowned physicist, created from a collection of photographs of numbers. Each detail contributes to a visual exploration of mathematics, perception, and pattern. The project took me two years to complete, photographing numbers in the most unusual places and objects, and bringing them together into a single portrait.


And a little secret: tucked inside the mosaic is a tiny portrait of me and my wife—a fun, hidden signature and a personal touch.

Limited edition posters and prints are available through my online gallery.

Humble, Yet Indispensable

A reed—sometimes called a “lamella”—is a thin strip of material that vibrates to produce sound in a musical instrument. Most woodwind reeds are cut from Arundo donax, the so-called giant cane.
Take that small, stubborn sliver away and the clarinet or saxophone becomes what it truly is: a hollow tube. No tone, no music—just breath wasted in polished plumbing.

The reed looks trivial, almost laughably so. A scrap of cane shaved to a sliver. Yet it is the only part that dares to vibrate. Without that fragile defiance, the instrument stays mute.

Humanity functions in much the same way. Each of us is a reed in a colossal instrument that calls itself civilization. Frail, replaceable, easy to overlook—yet necessary.

History loves to celebrate the instrument: the grand structures, the shining mechanisms, the impressive machinery. But the sound—when it happens—always begins with a thin piece of cane trembling under pressure.

When Straight Paths Bend

First, observe the alignment of the red circles as they move in a straight vertical path, up and down. Then keep your gaze on one of the three Xs in the middle. What do you notice?

© Thornton, I. M., Riga, A., Zdravković, S., & Todorović, D. (2025). The Mainz-Linez Illusion. I-Perception16(6). https://journals.sagepub.com/doi/10.1177/2041669525139912

The red circles seem to drift away from their true physical trajectories, as if they were following the curves of the static lines. This perceptual shift is known as the “Mainz-Linez Illusion“.

When you keep your gaze on the central X, the moving dots shift into peripheral vision, where spatial resolution is limited and detail is reduced. The visual system compensates by interpolating missing information based on contextual cues and prior experience. As a result, the dots become perceptually “bound” to the nearby curved lines, as if threaded on them, and their straight vertical motion is misread as oscillating.

The Mainz-Linez phenomenon reflects a broader principle: peripheral vision is largely constructive. Under certain conditions, this predictive filling-in can also distort motion judgments in real-world tasks—such as driving—where events in the periphery may be misperceived.

Enhancing Reader Engagement with Thought-Provoking Visual Content

As a visual creator, over the years I have developed a broad collection of mind games and hands-on activities designed to foster visual and critical thinking while supporting the learning of mathematics. These features, created for readers of all ages, are available for licensing to newspapers, magazines, and media platforms seeking distinctive, high-quality editorial content that captures attention and sustains reader interest.

Interested in adding a fresh editorial feature that energizes your publication? Explore the available offerings at Knight Features.