In this paper I contrast the metaphysical philosophies of Benedict de Spinoza and the ‘sudden enlightenment’ tradition of Chan Buddhism. Spinoza’s expressivist philosophy, in which everything can be conceived via a lineage of finite causes terminating in substance as a metaphysical ground of all things, emphasises the relative sameness of all entities. By contrast, Chan’s philosophy of emptiness, which rests on the dependent co-origination of all entities, renders such comparison fundamentally meaningless. Having no source beyond dependent co-origination to generate a thing’s distinct nature leads to a metaphysics in which, rather than being relatively similar or different, all things are at one and the same time absolutely the same and absolutely distinct. As a result, Spinoza grounds ethics wholly is sameness or similarity, whereas Chan transcends the dichotomy of sameness and difference and offers an environmental ethics grounded simultaneously in absolute sameness and absolute difference. As a result, in Spinoza’s case, the dissimilarity between human beings and the non-human world places limits on our concern for it. In Chan Buddhism, however, insight into the emptiness of all phenomena leads to a concern for all entities in their suchness, regardless of whether they are similar or different to human beings. As such, I argue that Chan is in a better position than Spinoza to develop a robust environmental ethic.