The philosopher and historian George Santayana once remarked that those who do not know their history are doomed to repeat its mistakes. A perusal of some of the essays will reveal that this is not always true. In some cases psychologists have known about mistakes of the past and sought to repeat them. But the recurrence can sometimes be fruitful: going round in circles can be a good thing, provided the circle is large that when one returns to the task one sees it in a new light and the error brings new insights.