The essay deals with Kant and how his view on rationailty determine's his view on morality, referring to his idea of duty

For Kant, the best way to live is the morally good way. This is not because of morality's bestowal to happiness, but because of the intrinsic value and significance of morality. The basic principles of morality are principles of practical reason; and these basic principles of practical rationality are 'a priori': our wisdom of these principles is not based on empirical observation or experience. On the contrary, these principles are in some sense 'built in' …

…is the law, or pure reverence for the law. Kant suggests that this law is: 'I ought never to act in such a way that I could not also will that my maxim should be a universal law'. The idea is that the law requires that one should act only on maxims that can serve as universal laws. One should in this way regard one's will as giving a universal law to all rational beings.