Democritus, the Laughing Philosopher

Rembrandt, The Young Rembrandt as Democritus the Laughing Philosopher (1628-1629)

According to convention there is sweet and bitter, a hot and a cold, and according to convention there is order. In truth there are atoms and a void.
~Democritus (ca 400 B.C.)

Democritus preached truth without proof more than 2000 years ago. He was forgotten but proven true in the modern age.