The mid-nineteenth century was a time when Bretonism and neo-Bardism were at their height in Western Brittany and for a century and a half this gave a new direction to Breton- language literature that was seeking to define, differentiate and distinguish itself from French literature. During this period, in 1848, Paul Lebreton wrote and published Studi var an astrou [study on the stars and planets], a treatise on astronomy in Breton to educate the people of Western Brittany about the march of the universe. This was probably the first scientific text ever published in Breton. However, the ‘unacknowledgement’ of this text in the annals of Breton literature and writing raises the question of the author’s intentions. Paul Lebreton was an author as unknown as his texts, so who was he really? And what were his influences and motivations? This study intertwines a literature review and archival/terminological research with a study of Lebreton’s astronomy approach to try and answer these questions. In addition, a comparison with other similar texts or schools of thought in Breton literature has led me to hypothesize that the Breton Enlightenment did take place, but hardly left any traces.