Learn about the discovery of Atoms with iMinds JNR audio learning series for younger minds. How is your body similar to the chair you are sitting in? Both things are made up of atoms! In fact, almost everything in the entire universe is made up of atoms. They are the building blocks of matter. In fifth century BC, the Greek philosopher Leucippus and his student Democritus were the first people to suggest the idea of atoms. Most of Greek society believed matter was made up of earth, fire, water and air. This belief was so popular it perpetuated for the next two thousand years.