The system which was taught by Aristotle at Athens in the fourth period
of his life, and which is now known as the Aristotelian philosophy, is
contained not in fragments but in extant books. It will be best then to
give at once a list of these extant works, following the traditional
order in which they have long been arranged, and marking with a dagger
([+]) those which are now usually considered not to be genuine, though
not always with sufficient reason.