If we are concentrating on the logic of predication, we shall easily come to the conclusion that this part of the history of logic is largely a story of error. For Aristotle, the ancestor of all logicians, began the development of this thought by formulating some masterly insights, but later rejected these insights and took a wrong direction. The consequences of his mistake were almost as fatal for his successors as the consequences of the first sin were for the heirs of Adam.