"disdainful of the Eckert-Mauchly mercenary approach. "Eckert and Mauchly are a commercial group with a commercial patent policy," he complained to a friend. "We cannot work with them directly or indirectly in the same open manner in which we would work with an academic group."80 But for all of his righteousness, von Neumann was not above making money off his ideas. In 1945 he negotiated a personal consulting contract with IBM, giving the company rights to any inventions he made. It was a perfectly valid arrangement. Nevertheless, it outraged Eckert and Mauchly. "He sold all our ideas through the back door to IBM," Eckert complained. "He spoke with a forked tongue. He said one thing and did something else. He was not to be trusted."81 After Mauchly and Eckert left, Penn rapidly lost its role as a center of innovation. Von Neumann also left, to return to the Institute for Advanced Study in Princeton. He took with him Herman and Adele Goldstine, along with key engineers such as Arthur Burks. "Perhaps institutions as well as people can become fatigued," Herman Goldstine later reflected on the demise of Penn as the epicenter of computer development.82 Computers were considered a tool, not a subject for scholarly study."