 If there is, in fact, a distinguishable privileged frame of reference in which the laws of mechanics take on a specially simple form, without that frame being determined in any way by relation to the matter distribution, a realist will find it hard to resist the temptation to view motions described in that frame as the ‘true’ or ‘absolute’ motions. If there is a family of such frames, disagreeing about velocity but all agreeing about acceleration, then the realist will feel a temptation to think of at least acceleration as ‘true’ or ‘absolute’. If such a realist believes motion to be by nature a relation rather than a property (and not all philosophers accept this; see the entry on  absolute and relational space and motion: classical theories,  section 1) then they will feel obliged to accord some sort of existence or reality to the structure – e.g., the structure of Galilean spacetime – in relation to which these motions are defined. For philosophers with such realist inclinations, the ideal relational account of motion would therefore be some version of Mach-heavy.