  Even if we now regard it as commonplace that his logic is but a fraction of the logic we know and use, Aristotle’s accomplishment was so encompassing that no less a figure than Kant, writing over two millennia after the appearance of Aristotle’s treatises on logic, found it easy to offer an appropriately laudatory judgment: ‘That from the earliest times logic has traveled a secure course can be seen from the fact that since the time of Aristotle it has not had to go a single step backwards…What is further remarkable about logic is that until now it has also been unable to take a single step forward, and therefore seems to all appearance to  be finished and complete’ (Critique of Pure Reason B vii).