  Where is the “elsewhere” where there would also be separation off, and where there are sun and moon “for them, just as with us”? Surprisingly, no ancient sources discuss this (although Simplicius, who quotes the fragment, is clearly puzzled by it, and argues for a neo-Platonic metaphysical interpretation). Modern commentators have suggested that the other worlds are on the moon and/or other planets (Jöhrens 1939, Zeller 1923), elsewhere on the face of our Earth (Cornford, 1934), or even contained within ourselves (and all other things) so that there are infinite worlds within worlds (Mansfeld 1980, Schofield 1996, Sisko 2003). There is also the possibility that Anaxagoras has no commitment to the reality of these other worlds, but is simply engaging in a thought experiment to show how the rotation would work (Fränkel 1969, Vlastos 1975, Schofield 1996).  There may be another possibility (Curd 2007). The unlimited rotation begins in a small area and expands indefinitely, pulling more and more of the unlimited mass of as-yet-unmixed ingredients into the whirl. Such an action could produce smaller local rotations within the larger whirl (especially at the expanding edges, as in the rotations of hurricane winds) and there, too, separation, mixture, and dissociation would occur. Such processes would result in the formation of systems like our own. This is not a thought-experiment on Anaxagoras’ part, but a commitment to the law-likeness of the rotations controlled by nous, and an awareness that similar processes will produce similar phenomena.  Our world-system is not unique in the universe, although there is but one universe (constituted by the entire limitless mass of ingredients).