Answer :
Solon.
Solon didn't exactly establish rule by assembly (Ecclesia) -- it already existed. However, the assembly was controlled by the upper classes. Solon allowed all the male citizens, including those belonging to the lowest class, to be a part of the ruling assembly.
The court (Heliaia) also already existed, but Solon enabled the men from the lower classes to sit as jurors.
Solon didn't exactly establish rule by assembly (Ecclesia) -- it already existed. However, the assembly was controlled by the upper classes. Solon allowed all the male citizens, including those belonging to the lowest class, to be a part of the ruling assembly.
The court (Heliaia) also already existed, but Solon enabled the men from the lower classes to sit as jurors.
