Consider a symmetric pyramid inscribed into a unit cube. It's volume is equal to 1/3. This was already known to Archimedes (287-212 BCE), and a visualization of this fact is shown here: First, we use Cavalieri's principle (which is very similar to Archimedes' method of exhaustion) and cut the pyramid in thin slices which are all shifted towards one corner of the cube. This does not change the volume of the pyramid. Then, the animation shows that three copies of this new pyramid indeed fill the cube.