Fire, derived from the energy locked up in molecules, was transformed from a destructive and devouring element to a friend of humankind over a period of what may have been several thousand years, some half a million years ago. We are the only animal species to have achieved this mastery over one of nature’s primeval attributes. Over the last 100 years we have been experimenting with the beneficial liberation of the energy that holds the particles of atomic nuclei together. At some stage in the future we may well take advantage of the energy that is stored in the form of the sub-atomic material particles themselves. As with all new developments, humans are required to re-examine their behaviour and answer the basic ethical questions posed by the need to achieve benefit and prevent harm from the unfolding opportunities. This process is particularly apt when confronted with the prospects of energy derived from the breaking down of atomic nuclei (nuclear fission) as the magnitude of the resulting effects is on a scale which presents unprecedented challenges to our control capabilities. But this is not different from the situation when we tamed the power of fire. It is just that, in nuclear engineering, we are at the beginning of a process which requires further expenditure of time and effort to achieve an equivalent level of control as we have in molecular engineering and incendiaries.