"When Hubbert presented the results at the Amsterdam conference, “it was very well received by the highest level technical people,” he recalled, “accepted completely, with no significant criticism.” After this vote of confidence, Shell organized training sessions on the new analysis for its field engineers. When it came time for the first course, Willis was away so Hubbert gave it himself. “What I discovered was that the theoretical argument was having no effect whatever on these men,” Hubbert recalled. The engineers were absolutely sure that the fractures were horizontal. Every article, every ad on fracking showed fractures oriented that way. They had been “completely brainwashed,” Hubbert thought. “They didn’t have any real evidence, but they’d been so thoroughly indoctrinated on this thing that they knew damned well these fractures were horizontal.” It mattered, because if they didn’t understand the forces at work, they couldn’t control it precisely. The technique would remain more art than science."