[2. Philosophic Relativity]. 2.1 The philosophical principle of the relativity of space means that the properties of space are merely a way of expressing relations between things ordinarily said to be 'in space.' Namely, when two things are said to be 'both in space' what is meant is that they are mutually related in a certain definite way which is termed 'spatial.' It is an immediate consequence of this theory that all spatial entities such as points, straight lines and planes are merely complexes of relations between things or of possible relations between things.
For consider the meaning of saying that a particle
is at a point
. This statement conveys substantial information and must therefore convey something more than the barren assertion of self-identity '
is
.' Thus what must be meant is that