<P> Purchas' account is again reflected by John Locke in his 1689 tract An Essay Concerning Human Understanding, introducing the story as attributed to Hindu mythology as a trope referring to the problem of induction in philosophical debate . Locke compares one who would say that properties inhere in "Substance" to the Indian who said the world was on an elephant which was on a tortoise, "But being again pressed to know what gave support to the broad - back'd Tortoise, replied, something, he knew not what". </P> <P> The metaphor is used as an example of the problem of infinite regress in epistemology to show that there is a necessary foundation to knowledge, as written by Johann Gottlieb Fichte in 1794: </P> <P> "If there is not to be any (system of human knowledge dependent upon an absolute first principle) two cases are only possible . Either there is no immediate certainty at all, and then our knowledge forms many series or one infinite series, wherein each theorem is derived from a higher one, and this again from a higher one, et., etc . We build our houses on the earth, the earth rests on an elephant, the elephant on a tortoise, the tortoise again--who knows on what?--and so on ad infinitum . True, if our knowledge is thus constituted, we cannot alter it; but neither have we, then, any firm knowledge . We may have gone back to a certain link of our series, and have found every thing firm up to this link; but who can guarantee us that, if we go further back, we may not find it ungrounded, and shall thus have to abandon it? Our certainty is only assumed, and we can never be sure of it for a single following day ." </P> <P> References to "turtles all the way down" have been made in a variety of modern contexts . For example, "Turtles All the Way Down" is the name of a song by country artist Sturgill Simpson that appears on his 2014 album Metamodern Sounds in Country Music . Turtles All The Way Down is also the title of a novel by John Green that was published on October 10, 2017 about a teenage girl with obsessive compulsive disorder, a condition he also has . </P>

Who said it's turtles all the way down