<P> A number of possible sources or inspirations for Jefferson's use of the phrase in the Declaration of Independence have been identified, although scholars debate the extent to which any one of them actually influenced Jefferson . Jefferson declared himself an Epicurean during his lifetime: this is a philosophical doctrine that teaches the pursuit of happiness and proposes autarchy, which translates as self - rule, self - sufficiency or freedom . The greatest disagreement comes between those who suggest the phrase was drawn from John Locke and those who identify some other source . </P> <P> There is debate about what the word "happiness" may have meant in 1776 . Current usage focuses on pleasant, positive emotions and having needs satisfied, whereas in 1776 the common meaning may have been "prosperity, thriving, wellbeing". </P> <P> In 1689, Locke argued in his Two Treatises of Government that political society existed for the sake of protecting "property", which he defined as a person's "life, liberty, and estate". In A Letter Concerning Toleration, he wrote that the magistrate's power was limited to preserving a person's "civil interest", which he described as "life, liberty, health, and indolency of body; and the possession of outward things". He declared in his Essay Concerning Human Understanding that "the highest perfection of intellectual nature lies in a careful and constant pursuit of true and solid happiness". </P> <P> According to those scholars who saw the root of Jefferson's thought in Locke's doctrine, Jefferson replaced "estate" with "the pursuit of happiness", although this does not mean that Jefferson meant the "pursuit of happiness" to refer primarily or exclusively to property . Under such an assumption, the Declaration of Independence would declare that government existed primarily for the reasons Locke gave, and some have extended that line of thinking to support a conception of limited government . </P>

Who wrote about the concepts of life liberty and property