Summary: To the old Gaels, the hazelnut was the nut of knowledge. Ruairidh has a story from the Isle of Skye about the knowledge that people can acquire from nuts. The tale features Sgàthach and Cuchullin and their battle against each other. Find out how the hazelnut played its part in this week’s letter. Find out more in this week’s letter. Accompanying Gaelic text, grammar points and vocabulary are all available at bbc.co.uk/litir