Most important advances in science come with a set of ethical dilemmas, but researchers must be careful to remain "science's masters" and not "at its mercy," says the Guardian's John Harris. Research into how the brain works, for example, could one day lead to treatments for disease and brain damage, but could also lead to brain manipulation for nefarious purposes. "The price of liberty may be eternal vigilance but we need science, not least because it is our most obvious source of the sort of innovation that saves lives and produces welfare," Harris says. "Our vigilance must be as much to ensure we don't stifle science as it is to be sure science remains our servant not our master."