A significant feature of Koestler's concept of holarchy is that it is open-ended, in both the macrocosmic and microcosmic dimensions. This aspect of his theory has several important implications. For example, if one were to take string theory to be legitimate, the holarchic system does not begin with strings nor does it end with the multiverse. Those are just the present limits of the reach of the human mind in the two dimensions. Humans will cross those limits eventually, because they do not encompass the whole of reality. In "Objective Knowledge" (1972), Karl Popper teaches that, what the human mind knows and can ever know of truth at a given point of time and space is verisimilitude—something "like" truth—and that the human mind will continue to get closer to reality but never reach it. In other words, the human quest for knowledge is an unending journey with innumerable grand sights ahead but with no possibility of reaching the journey's end.