In this quote by James Rachels, he discusses the concept of moral universalizability. According to Rachels, when we make decisions about how to treat others, we are essentially declaring that our actions should be considered as a universal law that applies to everyone. This means that when we treat someone a certain way, we are expressing the belief that this is how all people should be treated. Therefore, if we reciprocate the treatment that someone has given us, we are simply adhering to their own moral standards. This quote emphasizes the importance of consistency and fairness in our moral judgments and actions.