Gell-Mann classifies light mesons and spin-1/2 baryons with a scheme known as the eightfold way. The scheme relies on an approximate symmetry that is ultimately explained in terms of the symmetries of the three lightest quarks: the up, down and strange quarks.
What are Quarks:
Murray Gell-Mann talks about the history he discovers the quarks theory, and where the creative ideas come from:
Hermann Helmholtz, a German physicist, was one of the first, in the XIX century, to try to describe the creative process as a succession of steps, which he defined: saturation, incubation and illumination.
The French mathematician Jules Henri Poincare, in 1908, added a fourth phase: verification.
