Marcus Aurelius wrote the 12 books of the "Meditations" in Koine Greek as a source for his own guidance and self-improvement. It is possible that large portions of the work were written at Sirmium, where he spent much time planning military campaigns from 170 to 180. Some of it was written while he was positioned at Aquincum on campaign in Pannonia, because internal notes tell us that the first book was written when he was campaigning against the Quadi on the river Granova (modern-day Hron) and the second book was written at Carnuntum.