sentences:  His ideas are arguably more unsettling than Mainländer's notion of a will-to-die, yet strangely similar to Friedrich Nietszche's idea of the eternal return.Bahnsen developed a close friendship with fellow philosopher Karl Robert Eduard von Hartmann, until they eventually fell out and became philosophical rivals.This is not surprising, as both thinkers had similar philosophical beginnings and influences, yet differed crucially in their interpretation of these influences.