According to the POLLEX Project, a protoform (an ancestral form of a word) for "mana"—noted in historical-linguistic convention as *mana-"—existed in Proto-Oceanic, the precursor of many Pacific languages. Although the path through the tree from Proto-Oceanic to a specific language is not always clear, the word and concept are thousands of years old. According to linguist Robert Blust, "mana" means "thunder, storm, or wind" in some languages. Blust hypothesized that the term originally meant "powerful forces of nature such as thunder and storm winds" that were conceived as the expression of an unseen supernatural agency. As Oceanic-speaking peoples spread eastward, the notion of an unseen supernatural agency became detached from the physical forces of nature that had inspired it and assumed a life of its own.