Conversation so far:
what is the term for a legislature with two bodies
A bicameral legislature has legislators in two separate assemblies, chambers, or houses.
When did the bicameral legislature system originate?
The British Parliament is often referred to as the Mother of Parliaments because the British Parliament has been the model for most other parliamentary systems.

Question: What's the reasoning behind the system?
Self-contained rewrite: What is the rationale for bicameralism?