It is widely believed that while society allows technology to be private property, scientific knowledge is public and open. However, over the past quarter-century there has been increasing patenting of quite basic scientific knowledge. This essay argues that this is potentially a very serious problem. The future development of technology, as well as the future progress of science, is greatly facilitated when basic scientific knowledge is public and open. The paper explores the various factors that have led to the growing privatization of scientific knowledge. And it explores a variety of policy changes that can stop, and even reverse, these trends.