In this paper, the author offers a synoptic view of different theories of intergenerational justice, along two dimensions (savings/dissavings) and three modalities (prohibition, authorisation, obligation). After presenting successively the indirect reciprocity, the mutual advantage, the utilitarian and the Lockean approaches, special attention is given to the egalitarian theory of intergenerational justice. Two key differences between the egalitarian view on intergenerational justice and the sufficientarian interpretation of sustainability are highlighted.