The distinction between the systems of common law and equity rises from far long in history and could be understood properly by an examination of the origins of English law.
The common law is the law followed and gained by the Crown of England.
It could be traced back to 1066 when William of Normandy obtained the crown of England by defeating King Harold in the Battle of Hastings.
Before the Normans arrived, there was no such thing known as English law.
The Anglo-Saxon system of law was based on the local community.
Each area possessed its own system of courts where in the local customs were applied as common law.
The Normans were great administrators, and they undertook a process of centralization that created an accurate climate for the evolution of a uniform system of law for the entire country which is equally applicable as a rule of law.