One way to grasp something of the essence of Natural Law is to consider its history. Like most leading ideas in western thought, the first systematic presentation of Natural Law can be traced back to Plato and his star student, Aristotle. The latter is the more significant in this tradition, but it was Plato in The Republic who posited a moral order which embodies eternal laws, existing beyond the temporal world but binding upon this world.

However, the story begins even before these two thinkers, since they themselves drew, often in a spirit of opposition, from the work of the first and probably most remarkable group of philosophers, Heraclitus and the Sophists. Now known as the pre-Socratics, these men date back to 585 BC – a curiously precise and therefore nominal date handed down by tradition – and they built upon each others' ideas up until Plato's time. None of their own writings exist, and their ideas are known entirely through fragmentary quotations and descriptions by later figures. In many ways they can be seen as the most original thinkers in the entire western philosophy, and a link with the eastern. Heraclitus, known as ‘the Obscure’, was the most seminal of them all, and it is no exaggeration to say that he initiated many of the fundamental questions which have preoccupied Western philosophy down through the centuries.