Leucippus (Elea 500 active Abdera ??) and Democritus (460 BC Abdera – Abdera370 ac) are two pre-Socratic philosophers considered founders of the atomistic school.

Leucippus and Democritus, teacher and student, performed one of the greatest contributions to scientific thought in introducing the concept of atom and void:

(1) "The atom is the particle which are made all things and indivisible, mobile and imperishable. Therefore the existence of the atom implies the existence of vacuum since the contrary could not move atoms"

(2) "The various ratios of atoms and vacuum of every body give the special characteristics to the elements of nature and the living beings."