“...What can we learn about the fourth dimension by studying geometrical relationships within our space? What should be the relationship of a three-dimensional body to a four- dimensional one? A four-dimensional body as the trace of the movement of a three-dimensional body in a direction not contained in it. A four-dimensional body as composed of an infinite number of three-dimensional bodies. A three-dimensional body as a section of a four-dimensional one. Parts of bodies and whole bodies in three and in four dimensions. Incommensurability of a three- dimensional and a fourdimensional body. A material atom as a section of a four-dimensional line. If we examine the profound difference that exists between a point and a line, between a line and a surface, between a surface and a solid, i.e. the difference between the laws which govern a point and a line, a line and a surface and so on, and the difference of phenomena which are possible in a point, a line, a surface, we shall realize how many things, new and incomprehensible for us, lie in the fourth dimension...”
“...What can we learn about the fourth dimension by studying geometrical relationships within our space? What should be the relationship of a three-dimensional body to a four- dimensional one? A four-dimensional body as the trace of the movement of a three-dimensional body in a direction not contained in it. A four-dimensional body as composed of an infinite number of three-dimensional bodies. A three-dimensional body as a section of a four-dimensional one. Parts of bodies and whole bodies in three and in four dimensions. Incommensurability of a three- dimensional and a fourdimensional body. A material atom as a section of a four-dimensional line. If we examine the profound difference that exists between a point and a line, between a line and a surface, between a surface and a solid, i.e. the difference between the laws which govern a point and a line, a line and a surface and so on, and the difference of phenomena which are possible in a point, a line, a surface, we shall realize how many things, new and incomprehensible for us, lie in the fourth dimension...”