For its significant role in legitimizing the Philippine revolution in 1898, the place of Apolinario Mabini’s “True Decalogue” in Philippine history is already well secured. In this essay, I, however, demonstrate the continuing relevance of this work in current discussions on the morality of nationalism. After explicating its arguments for why nationalism should be regarded as a moral imperative, I explore how it handles the issue concerning the moral justifiability of national partiality—referring to the partiality of a person to the interests of his/her own country and co-nationals. Using a combination of content, logical, and comparative types of analysis as a method, I first exhibit the philosophical character of this work in terms of both substance and form, after which I compare and contrast of its insights and views with some other perspectives on the morality of nationalism. In the main, I show that Mabini’s work endorses a universalist type of nationalism, utilizes both instrumentalist and non-instrumentalist modes of reasoning, and anticipates some of the critical considerations in reconciling national partiality with the standard view, called moral universalism, which states that moral principles should apply equally to persons of all kinds.