The Mabinogion is a collection of prose stories from medieval Welsh manuscripts. They are partly based on early medieval historical events, but almost certainly hark back to older Iron Age traditions. Its name comes from a misunderstanding made by the Mabinogion's first English translator, Lady Charlotte Guest: she found at the end of the first tale the form mabynnogyon, a scribal error that was assumed to be the plural of the Welsh word mabinogi, which occurs correctly at the end of the remaining three of the Four Branches. The word mabinogi itself is something of a puzzle, although it is ultimately related to the Welsh mab, which means "son, boy." Professor Eric P. Hamp, however, suggests that mabinogi derives from the name of the Celtic deity Maponos ("the Divine Son"), and originally referred to materials pertaining to that god. Strictly speaking, "Mabinogi" applies only to the Four Branches (see below), which are speculated to have derived from older tradition. Each of these four tales ends with a colophon meaning "thus ends this branch of the Mabinogi" (in various spellings), hence the name.