The aim of this paper is to defend the Kantian normative idea of aspiring towards maturity, freedom, and universal morality, against a recent criticism of Kant’s tree analogy, put forward by Morten Korsgaard. The aim is not to defend the tree analogy as such. Neither is it an attempt to argue against metaphors as such. It is rather to point out a more general problem of building an argument from the use of metaphors as premises, and to highlight the necessity of separating content from logical form, as well as descriptive empirical assumptions from normative aspirations. I first give summary of Kant’s tree analogy and give it some context in relation to more mechanistic analogies as well as more atomistic social contract ideas from the enlightenment. Secondly, I point out some general problems of using metaphors as premises for building an argument. In the third part I turn to what I think are the more particular problems in Korsgaard’s reasoning about Kant’s analogy in relation to what Korsgaard refers to as “the capitalist logic of progress”. Finally, I will end the paper by showing why Kant's aspiration for maturity is worth defending.