A leap of faith, in its most commonly used meaning, is the act of believing in or accepting something not on the basis of reason. The lack of applying reason might be because the thing being believed or accepted lies outside the boundaries of reason. Overview The phrase is commonly attributed to Søren Kierkegaard; however, he never used the term, as he referred to a qualitative leap. A leap of faith according to Kierkegaard involves circularity insofar as the leap is made by faith. In his book Concluding Unscientific Postscript, he describes the core part of the leap of faith: the leap. “Thinking can turn toward itself in order to think about itself and skepticism can emerge. But this thinking about itself never accomplishes anything.” Kierkegaard says thinking should serve by thinking something. Kierkegaard wants to stop "thinking's self-reflection" and that is the movement that constitutes a leap. He is against people's thinking about religion all day without ever doing anything; but he is also against external shows and opinions about religion. Instead, Kierkegaard is in favor of the internal movement of faith. He says, "where Christianity wants to have inwardness, worldly Christendom wants outwardness, and where Christianity wants outwardness, worldly Christendom wants inwardness." But, on the other hand, he also says: "The less externality, the more inwardness if it is truly there; but it is also the case that the less externality, the greater the possibility that the inwardness will entirely fail to come. The externality is the watchman who awakens the sleeper; the externality is the solicitous mother who calls one; the externality is the roll call that brings the soldier to his feet; the externality is the reveille that helps one to make the great effort; but the absence of the externality can mean that the inwardness itself calls inwardly to a person - alas - but it can also mean that the inwardness will fail to come." The "most dreadful thing of all is a personal existence that cannot coalesce in a conclusion," according to Kierkegaard. He asked his contemporaries if any of them had reached a conclusion about anything or did every new premise change their convictions. David F. Swenson described the leap in his 1916 article The Anti-Intellectualism of Kierkegaard using some of Kierkegaard's ideas. This is how the leap was described in 1950 and then in 1960. The leap into sin and into