The doctrine that all relations are internal was a cardinal thesis of absolute idealism, and a central point of attack by Moore and Russell. It is a kind of essentialism, stating that if two things stand in some relationship, then they could not be what they are did they not do so. If, for instance, I am wearing a hat now, then when we imagine a possible situation that we would be apt to describe as my not wearing the hat now, we would strictly not be imagining me and the hat, but only some different individuals (see also counterpart). Moore (‘External and Internal Relations’, Proceedings of the Aristotelian Society, 1919–20) believed the doctrine to depend upon the simple fallacy of inferring from ‘necessarily, if I am wearing a hat then I am wearing a hat’ that ‘if I am wearing a hat I am necessarily wearing a hat’. It is, however, clear that a more complex combination of thoughts underlay the idealist doctrine, including the holistic doctrine that the properties of individuals are in some sense secondary to the properties of the whole universe in which they exist, together with an epistemological mistrust of separating what is known from the knowing mind. The combination gave some motive for holding that everything gains its identity simply as an aspect of one indivisible, Parmenidean whole. The rejection of this in favour of a more atomistic conception of the world as a loose plurality of individuals, allowed external relations, these being relations which individuals could have or not depending upon contingent circumstance.