About 500 B.C., early Greeks suggested that all things and beings were assemblages of  identical and minutely small elements. They named these elements "atoms," which mean "indivisible."

These intuitive Greek thinkers had no tools or laboratories. They had reached their conclusion through mere philosophical deduction. Their Atomism was so remote from the way we commonly experience the world, that it took twenty four centuries to be fully accepted.

Through the years, the Greek atom was subjected to major conceptual surgery. The most serious occurred when it was discovered that its own name was not deserved. The so-called  "indivisible" atom was found to be made of  electrons revolving at a great distance around a nucleus composed of protons and neutrons. The atom, once assumed to be the smallest of all things, had become a giant in relation to some of its parts. Thus, begun the investigation of subatomic particles.

For scientists used to the predictability of the macrocosm, the subatomic world was puzzling. It had an inexplicable dual nature: as particles, it formed tangible substances; as waves, it spread energy into space. In addition, whereas ordinary matter could easily be measured, elementary matter was elusive. Researchers had to deal with probability instead of certainty, an uncomfortable situation for objective science. A new theory was elaborated. It was named "Quantum Theory," after the "quanta",   energy packets that atoms captured or emitted.

Physicists have engaged into a complex journey toward absolute smallness. On their way, they have discovered many minute crumbs: electrons, protons, neutrons, positrons, photons, hadrons, leptons, mesons, pions, gluons and more. Yet, objective science has its limits.  Researchers, as they approach the true essence of matter,  have realised that the primary  instruments they are using— their own brain— is meddling with their findings.

Fortunately,  as proven by early Greeks and others after them,  intuition and deduction are formidable tools. They suffice to unveil this truly ultimate building block of the universe: the Eternon.