A fallacy of aristotle's about ends

A distinction between activities and processes plays an important role in Aristotle's argument to establish that the good life is a life of activities, among which metaphysical contemplation is foremost. But, as a result of having failed to distinguish internal from external ends of action, Aristotle makes fallacious inferences from every activity's having an internal end in itself to its possessing features which may be legitimately inferred only from external ends, and from every process's having an internal end that is its terminal point to its having the attainment of that terminal point as an external end. The resulting confusion explains a number of problematic elements in Aristotle's ethical theory.