The year after his arrival at Clermont-Ferrand Bergson displayed his ability in the humanities by the publication of an edition of extracts from Lucretius, with a critical study of De Rerum Natura, issued as Extraits de Lucrèce, and of the materialist cosmology of the poet (1884). Repeated editions of which attest to its value in promoting Classics among French youth. While teaching and lecturing in this part of his country (the Auvergne region), Bergson found time for private study and original work. He crafted his dissertation "Time and Free Will", which was submitted, along with a short Latin thesis on Aristotle ("Quid Aristoteles de loco senserit", "On the Concept of Place in Aristotle"), for his doctoral degree which was awarded by the University of Paris in 1889. The work was published in the same year by Félix Alcan. He also gave courses in Clermont-Ferrand on the Pre-Socratics, in particular on Heraclitus.