18. They were asked whether they did not want to make some use of their knowledge, since it is not enough to take pleasure in knowledge, but this must serve a purpose, which is its end in view. Knowledge alone would not serve any purpose for them, but would for others, if they were willing to share their knowledge with them. They were told that anyone who wants to be considered wise ought never to stop at acquiring knowledge, since these are merely auxiliary causes intended to assist the discovery of matters that will affect behaviour. But they replied that they take pleasure in acquiring knowledge, and that is for them is its purpose.