The steps go something like this: From experience to the discovery of objectivity, then from objectivity to the discovery of functioning. Functioning is what underlies objectivity and as a category it subsumes it. What arises as objectivity is dissolved into functioning - it is not things as such, but their action. The next step is to the subject as the do-er of the functioning - it is inferred but not seen - thought of as necessary to provide or explain the coherence of functioning. It is the thing-in-itself but thought of from the point of view of functioning being taken as the truth of experience. Finally there is the necessary impossibility of the subject ever appearing. This is as far as it can go. The mind keeps on worrying at it, a self keeps on being inferred, speculated. The realisation that there cannot be a self as a subset of, or distinction in, functioning remains an asymptote, approach it and there is no more will to bring it about. All interest and purpose melts away, and would lead to a sort of nihilism if it wasn't soon realised that nihilism is a last redoubt of the separate subject. Rather see, with that annoyingly smug logic, that since purpose is no purpose therefore it is purpose.