The term ‘ aporia’ (perplexity, impasse, obstacle, doubt, puzzle) is frequent throughout Aristotle's works. This essay summarises Aristotle's explicit accounts of aporia, then explores the various roles it plays in his inquiries into nature. There follow some suggestions about ways in which study of current establishment and pursuit of scientific agendas might profit from reflection on the diverse modes and functions of perplexity. The final section reflects on the Aristotelian link between perplexity and eudaimonia (wellbeing, self-fulfilment, blessedness).