While it is difficult to draw a distinction between Roman and Byzantine soldiers from an organizational aspect, it is easier to do so in terms of their social profile. The military handbooks known as the Taktika continued a Hellenistic and Roman tradition, and contain a wealth of information about the appearance, customs, habits, and life of the soldiers. As with the peasantry, many soldiers performed ancillary activities, like medics and technicians. Selection for military duty was annual with yearly call-ups and great stock was placed on military exercises, during the winter months, which formed a large part of a soldier's life. Until the 11th century, the majority of the conscripts were from rural areas, while the conscription of craftsmen and merchants is still an open question. From then on, professional recruiting replaced conscription, and the increasing use of mercenaries in the army was ruinous for the treasury. From the 10th century onwards, there were laws connecting land ownership and military service. While the state never allotted land for obligatory service, soldiers could and did use their pay to buy landed estates, and taxes would be decreased or waived in some cases. What the state did allocate to soldiers, however, from the 12th century onwards, were the tax revenues from some estates called pronoiai (). As in antiquity, the basic food of the soldier remained the dried biscuit bread, though its name had changed from boukelaton () to paximadion. Teachers Byzantine education was the product of an ancient Greek educational tradition that stretched back to the 5th century BC. It comprised a tripartite system of education that, taking shape during the Hellenistic era, was maintained, with inevitable changes, up until the fall of Constantinople. The stages of education were the elementary school, where pupils ranged from six to ten years, secondary school, where pupils ranged from ten to sixteen, and higher education. Elementary education was widely available throughout most of the Byzantine Empire's existence, in towns and occasionally in the countryside. This, in turn, ensured that literacy was much more widespread than in Western Europe, at least until the twelfth century. Secondary education was confined to the larger cities while higher education was the exclusive provenance of Constantinople. Though not a society of mass literacy like modern societies, Byzantine society was a profoundly literate one. Based on information from an extensive array of Byzantine documents from different periods (i.e. homilies, Ecloga,