Normative ethics asks: What makes right acts right? W. D. Ross attempted to answer this question in The Right and the Good (1930). Most theorists have agreed that Ross provided no systematic explanatory answers. Ross's intuitionism lacks any decision procedure, and, as McNaughton (2002: 91) states, it ‘turns out after all to have nothing general to say about the relative stringency of our basic duties’. Here I will show that my own Rossian intuitionism does have a systematic way of explaining what makes right acts right. Deontological theories have struggled to say what internal to acts could make them right. From Price to Ross, the striking but uninformative answer has been the nature of the act. In this paper I will provide a Rossian theory of the moral natures of acts. It contains a set of self-evident principles of moral stringency and other considerations that can assist agents in deciding what prima facie duty overrides what.