Rocks have “eyes.” Not like human eyes, but a “grain”; areas apparent to savvy masons looking for easy places to split the rock.

No matter how you strike it, stones always seem to split the same way. Fascinating, isn’t it? But that’s not always true. A block of granite has a direction into which it easily splits, and one which takes more effort to crack.

The reason is inside the stone itself. Granite forms when magma slowly cools and hardens deep underground over long periods of time. Inside, granite is full of many tiny cracks that are almost invisible to our eyes. When enough force is applied at the right angle in relation to those cracks, it creates brittle areas in a certain direction. That direction is called the “grain.”

The interesting thing is that microscopes weren’t available for ancient stonemasons to use. All they had was their eyes and the bare stone. Despite that, experienced masons gauged their properties, pinpointing the right place to cut.

They then opened small holes along the grain, gradually hammering in wedges. As the force reaches deep into the stone, a single crack forms. Imagine that – entire boulders were broken thanks to lines envisioned by humans.

However, masons saw more than just the grain. They spotted irregularities and impurities, which guided the process of considering where to apply force. Sometimes this meant opening more holes and even going against the grain.

They repeated this process of judging the rock’s composition and purposefully cracking. A single mistake could create additional cracks, rendering the stone useless.

So, consider the rock at the entrance. Does it have a grain? Naturally, it does. That small stone you just touched was once part of a huge boulder, and like its parent, it too has a brittle grain.

You may not see it, but tracks run deep within stone. It has depths beyond what you see at a glance.