By the end of 1950, Pauling was widely seen as a security threat and a defender of Communism -- if not an outright Communist -- while American boys were dying in Korea. He received a steady stream of hate mail. He remained under investigation both by the FBI and within Caltech, where a committee of faculty members and trustees had been convened to examine his affiliations and activities -- a way of mollifying unhappy conservative school trustees.

Then came more bad news. Pauling had served as a scientific consultant to the Eli Lilly pharmaceutical company since 1946 and was being paid a substantial sum for his advice. In 1950 the firm cancelled his contract. "No reason was given," Pauling said, "but I was later told by the assistant director of research and the former director of research that the contract had been cancelled because of my political activities."

The same year, the Office of Naval Research withdrew an invitation to Pauling to chair a committee to help plan future chemical research. The only good news came late in the year, when the Caltech internal committee concluded its work, finding no evidence that Pauling was a member of the Communist Party, and none that he had been guilty of an malfeasance. Although a few trustees still felt strongly that Pauling should be fired, the faculty members had successfully argued that discharging one of the school’s leading figures without evidence of wrongdoing would be seen as disgraceful by scientists worldwide.

Through it all, Pauling seemed unbowed. He kept up a heavy schedule of public speeches for peace, raised money for Sidney Weinbaum’s defense, served as a parole advisor for Dalton Trumbo (one of the Hollywood Ten), and joined another left-wing group, the American Association of Scientific Workers. It seemed, for awhile, that no amount of pressure would alter his dedication to his political principles.