-space is
This is the well-known equation of continuity. Now equation (4) shows that if this equation holds for the space of any time-system, it holds for the spaces of all time-systems.
When the equation of continuity holds, the 'charge' of any extensive component of the material object under consideration never varies. Hence it is a mere matter of words and definition whether the charge is said to be mediately possessed by the object or immediately possessed.
[8]Cf. [subarticle 37.3], Chapter X, Part III.
[9]Cf. Principia Mathematica.
[CHAPTER XVI]
CAUSAL COMPONENTS
[60. Apparent and Carnal Characters]. 60.1 Are there any material objects in nature? That there are such bodies is certainly an assumption habitually made in the applications of mathematics. But the assumption does not supersede the necessity for enquiry.
We may roughly summarise the properties of material objects, as here defined, by saying that they should be continuous both in time and in space. But this is just what ordinary perceptual objects appear to be. Now perceptual objects are what they appear to be; for a perceptual object is nothing else than the permanent property of its situations, that they all shall exhibit those appearances. Accordingly if a perceptual object appears to be a material object, it is a material object.