Greek philosophy emphasized the distinction between « nature » (physis, φúσις) on the one hand and « law », « habit » or « convention » (nomos, νóμος) on the other. [ref. needed] It is expected that what the law commands will vary from place to place, but what was « by nature » should be the same everywhere. A « law of nature » would therefore smack of paradox rather than something that obviously exists.  Against the conventionalism that could produce the distinction between nature and habit, Socrates and his philosophical heirs, Plato and Aristotle, postulated the existence of natural justice or natural law (dikaion physikon, δίκαιον φυσικόν, Latin ius naturale). Among these, Aristotle is often referred to as the father of natural law.  Aristotle`s association with natural law may be due to Thomas Aquinas` interpretation of his works.  But whether Thomas Aquinas correctly read Aristotle is controversial. According to some, Thomas Aquinas mixes natural law and natural law, which Aristotle postulates in Book V of the Nicomachean Ethics (Book IV of the Euremic Ethics). He admired him as a patriot, valued his opinion as a moral philosopher, and there is little doubt that he regarded the life of Cicero, with his love of study and aristocratic life in the country, as a model for his own.  Jefferson described Cicero as « the father of eloquence and philosophy. »  The development of this tradition of natural justice into a tradition of natural law is generally attributed to the Stoics. Natural law first appeared among the Stoics, who believed that God is everywhere and in everyone (see classical pantheism).
According to this belief, there is a « divine spark » in man that helps him to live in harmony with nature. The Stoics felt that there was a way in which the universe had been designed, and that natural law helped us to enter into harmony with it. Sir Alberico Gentili and Hugo Grotius based their philosophy of international law on natural law. In particular, Grotius` writings on the freedom of the seas and the theory of just war were directly inspired by natural law. Of natural law itself, he wrote that « not even the will of an omnipotent being can change or abolish natural law, » which « would retain its objective validity even if we were to assume the impossible, that there is no God, or that he does not care about human affairs. » (De jure belli ac pacis, Prolegomeni XI). This is the famous argument etiamsi daremus (non esse Deum), which no longer made natural law dependent on theology. German church historians Ernst Wolf and Mr. Elze, however, disagreed, arguing that Grotius` concept of natural law had a theological basis.  According to Grotius, the Old Testament contained moral commandments (e.g., the Decalogue) that Christ affirmed and were therefore still valid. In addition, they were useful in explaining the content of natural law.
Biblical revelation and natural law come from God and therefore cannot contradict each other.  Examples of positive law include rules such as the speed at which individuals are allowed to drive on the highway and the age at which individuals can legally purchase alcohol. Ideally, when drafting positive legislation, governing bodies should base it on their sense of natural law. Since natural law presupposes universalizing rules, it ignores the fact that different people or cultures may see the world differently. For example, if people interpret differently what it means when something is fair or equitable, the results will be different.