In the history of science, there are few real eureka moments, but this came pretty close. “It wasn’t just some gradual process where it slowly dawned on us,” Doudna says. “It was an oh-my-God moment.” When Jinek showed Doudna his data demonstrating that you could program Cas9 with different guide RNAs to cut DNA wherever you desired, they actually paused and looked at each other. “Oh my God, this could be a powerful tool for gene editing,” she declared. In short, they realized that they had developed a means to rewrite the code of life.4
