This study can be read as an introduction to the spiritual world of island Melanesia, from the particular angle of etymology, or "linguistic archaeology". It should be of interest to linguists, but also to anthropologists and other scholars in social sciences, with no specific background in linguistics. My aim will be to show that lexical comparison among unwritten languages can provide valuable insights in the domain of ethnographic analysis and culture history. In proposing etymological hypotheses, scholars need to constantly bear in mind the risk of proposing false etymologies based on mere similarity or impressionistic likelihood. This is where the power of the Comparative method becomes crucial, as it defines a solid methodology based on the observation of regular sound correspondences, as well as the identification of convincing semantic links.