Over the nearly fifteen hundred years of the empire's existence, different titles were adopted and discarded, and many lost or gained prestige. By the time of Heraclius in the 7th century many of the early Roman titles, grounded in the Latin language and the traditions of the old Roman republic had become obsolete in the now mostly Greek-speaking empire, although Latin survived longer in law and in the military. Heraclius formally changed the official language to Greek from Latin in 610. Titles inspired by their Greek tradition, often only rough approximation of Latin concepts, became common (i.e. "basileus" instead of "caesar" or "augustus" for the title of the emperor himself). Other titles changed meaning (for example, "Patriarch") or were devalued with time (such as "consul").