Four-dimensional Space - Cross-sections

Cross-sections

As a three-dimensional object passes through a two-dimensional plane, a two-dimensional being would only see a cross-section of the three-dimensional object. For example, if a balloon passed though a sheet of paper, a being on the paper would see a circle gradually grow larger, then smaller again. Similarly, if a four-dimensional object passed through three-dimensions, we would see a three-dimensional cross-section of the four-dimensional object–for example, a sphere.