 The first version of the distinction is owed to Moore. According to Moore’s (1919: 47), a binary relation \(R\) is internal iff if \(x\) bears \(R\) to \(y\) then \(x\) does so necessarily. From the internality of \(R\), in Moore’s sense, it follows that if \(x\) exists at all then \(x\) indeed bears \(R\) to \(y\). But if it’s possible that \(x\) exist whilst failing to bear \(R\) to \(y\), then \(R\) is external. The doctrine of the necessity of origin provides one putative example of a relation that’s internal in Moore’s sense. If you essentially come from your biological parents then you could not have existed whilst failing to be their offspring, i.e., the relation of biologically originating from must be internal in Moore’s sense.