According to the feudal theory exemption from tolls must be granted in certain cases. Supplies for the army and navy, for the king and higher officials, for churches, hospitals, and monasteries, should pay no toll. Scholars at the universities enjoyed in theory an immunity which they could not secure in fact. The merchant, however, was always regarded as fair prey, and wares of commerce which were supposed to be exempt, as in France, for instance, wares on their way to Lyons fair, enjoyed only partial immunity. A sixteenth-century French writer instances as an example of the oppression of tolls the case of a merchant who shipped to the East some cloth that was wet on the voyage and had to be sent back to Paris to be redyed; all along the road in France the tolls had to be paid over again. The collectors levied toll even on grain that was being taken to mill, on cattle that were to be used as plow animals, on agricultural implements and manure. =68. Development of the toll system.=—With the growth of commerce the toll-stations of course increased in value; and the practice grew up of leasing them to contractors, who paid a high sum for the privilege and had to devise, an old author tells us, “ten thousand new and unusual tyrannies, frauds and exactions” to make any profit for themselves. Many kept taverns, and managed to detain the merchant for days on various pretexts, such as absence of the proper official. Some made the merchant pay to be relieved of the necessity of having his wares unpacked and weighed and measured in detail. Many kept the tariff secret, and extorted what they could on every occasion. Some lived far from the highway, and some put their offices by design on impracticable roads, and fined the merchants heavily who went by another route. On some routes, as along the middle Rhine, Bingen to Coblenz, it was almost impossible for commerce to be carried on except along the river, and very heavy tolls could be levied here without danger of the merchants escaping; but under other conditions the collectors established wings, as they were called, secondary offices on the side-roads to prevent evasion of the toll. Some collectors established regular pools, to use the modern term applied to railroad combination; twenty-five or thirty of them, representing perhaps five or six separate toll-areas, associated and agreed upon their rates; then they pooled and divided their profits. =69. Constraint of trade by tolls.=—The establishment of toll-stations put an artificial constraint on trade, which kept it in the paths most convenient for the collectors, not most suitable to the merchants. Lords would not allow new and better roads to be built, for fear that profits on the old roads would be impaired. The compulsion to follow certain routes (German _Strassenzwang_) became a serious evil as commerce developed and sought new openings; and the loss to the public was far greater than any gain by the toll receiver.