The main text for addressing the concept of 'substitution' is Levinas's essay of the same name. The essay exists in two versions. The first version was delivered as a lecture in Brussels in November 1967 and was revised for publication in the Revue Philosophique de Louvain in the following year (bwp 79-95). Although the essay was published on its own, as a lecture it had been preceded the day before by a reading of 'Proximity', the contents of which are familiar from the text of 'Language and Proximity' (cp 109-26). The second and better known version of 'Substitution' was published in 1974 as the central chapter of Otherwise than Being or Beyond Essence (ob 99-129). I shall focus on the first version of 'Substitution' in the conviction that Levinas's train of thought is more readily identified in his initial formulation of it, referencing the second version only when it departs from the first in some significant way.