Which enlightenment philosopher first popularized the concept of separation of powers among government branches?

Baron de Montesquieu

Montesquieu was a French political philosopher (1689-1755), very famous for popularizing the separation of powers, in his work The Spirit of the Laws (1748), a treatise on political theory.

In the treatise, the philosopher describes the three types of government: democracy, republic, monarchy and despotism, and supported the separation of powers into three branches: legislative, executive, and judiciary branch which should rule under the law and check each other’s power, preventing from corruption.

This theory set the base for many of the actual governments.

25. twelve tables

26. having important positions chosen by lot