A nucleon is a neutron or a proton. Both particles are found in the nucleus of atoms and are bound together by the strong force. Protons and neutrons, along with many other subatomic particles which were once thought to be elementary (that is, not built up from smaller constituents), are now known to be composed of quarks – three quarks to each nucleon. As for the origin of the name, physicist C. Moller wrote in 1941: "Following the original proposal of Belinfante, the writer has used the word 'nuclon' as a common notation for neutrons and protons. In the meantime, however, it has been pointed out to me that, since the root of the word nucleus is 'nude', the notation nucleon would from a philological point of view be more appropriate."