This etymology, as the standard one, sees in the first syllable of κειμήλιον the verb κεῖμαι "to lie". But it offers a very original explanation for the end of the word, which is assumed to be a compound of the negation μή + ἥλιος: since treasures are stored in a room away from the sight of anyone, they are thereby not exposed to daylight and are "without sun". There are a few other instances of words etymologized as compounds with μή, although not many (see μἰσος / μή + ἴσος, μήνη / μή + μένω, μῆνις / μή + ἕν). The original feature here is that this assumed compound is itself integrated into a compound of superior level, in a Cratylean fashion.