Regarding Sól's attested personifications in Norse mythology, John Lindow states that "even kennings like 'hall of the sun' for sky may not suggest personification, given the rules of kenning formation"; that in poetry only stanzas associated with Sól in the poem "Vafþrúðnismál" are certain in their personification of the goddess; and "that Sól is female and Máni male probably has to do with the grammatical gender of the nouns: Sól is feminine and Máni is masculine." Lindow states that, while the Sun seems to have been a focus of older Scandinavian religious practices, it is difficult to make a case for the placement of the sun in a central role in surviving sources for Norse mythology.