 By contrast, consider the following two principles: (i) Every event is preceded by another event that is its cause; (ii) The relation \(x\) precedes \(y\) is irreflexive (nothing precedes itself), asymmetric (if \(a\) precedes \(b\) then \(b\) does not precede \(a\)) and transitive (if \(a\) precedes \(b\) and \(b\) precedes \(c\) then \(a\) precedes \(c\)).