A discussion of one of Saussure's unpublished notebooks dating from a time shortly before the courses that have resulted in the Course in general linguistics. The notebook is about an unsolved problem with the poetic base of Saturnian verses, which is treated within the philological context of Saussure's time. As such it offers new insight into the philological background of Saussure's linguistic work. In passing, a poem written by Saussure, and illustrating his position, is published here for the first time.