It is the purpose of this paper to explain the fact that in the inter-atomic transfer of energy, whilst the quantitative aspect of the transfer seems to demand a corpuscular theory of energy, the qualitative aspect, (i.e. the path traken by the energy) seems to demand a wave theory. The suggested explanation may be summarised thus: hypothesis (i) During the transfer process corpuscles and electromagnetic waves both exist, but the energy resides solely in the corpuscles. Hypothesis (ii) The presence of the electromagnetic fieldinvolves a distortion of space-time, and the patbstaken by the corpuscles are determined by the condition that they must correspond to geodesics in this distorted spacetime. [...]