There is a Persian proverb that ‘the King has many eyes and ears.’ In every state the king must have means of knowing through his trusted officers, who see and hear for him, what is going on among the people. But in Persia the arrangements for obtaining information of this kind were reduced to a science. Satraps and people alike were constantly watched by a body of spies, and so secretly was this done that it was not even known who were the officers employed. A favourite device of the spies was to feign a friendship for the person whose actions they wished to report, and a man might be arrested and executed without once suspecting the false friend who had given information of his real or imaginary guilt. Sometimes the spy would denounce an innocent man for no other reason than to bring himself into notice as active in the King’s service. Another plan was to take note of every one who passed along the roads which led from the various Residences of the Great King to the other principal towns of the empire. These roads were commanded by fortresses where officers were stationed whose duty it was to enquire of every wayfarer whither he was going and on what errand, and any messenger carrying a letter was obliged to give it up for inspection. This was intended to check the free passage of suspicious persons, and to prevent the sending of letters not approved by the government; but it must often have been easy to find means of evading the King’s officers. In order that the King might be informed as quickly as possible of any risings or disturbances in the provinces, a very complete system of postal communication had been arranged. Besides the fortresses, there were stations all along the roads, at intervals of about fifteen miles apart, where the traveller could find shelter for the night. Here the swiftest horses and horsemen were always waiting in readiness to carry on the post at full gallop without a moment’s delay, whether in burning sun or blinding snow: and thus there came to be a saying that ‘the Persian post-riders fly faster than the cranes.’ A messenger sent from Susa to Sardis, traveling at the ordinary speed, would take a hundred days to reach his destination; but by means of the King’s posts a letter could be conveyed in six or seven days and nights. It must not be supposed, however, that ordinary letters were carried so fast. The King’s posts were entirely reserved for the King’s business, and by this means he had the advantage of getting news from the provinces and sending back his commands before any one else knew what was going on.