The most famous schools for medicine were at Croton, Cnidus, Rhodes, and Cos, where the name of Hippocrates is celebrated as the founder. These schools were guilds or trade unions, into which the apprentice entered with a very remarkable and solemn oath. Such accredited physicians were specially exempted by law, in some cities, from prosecution for manslaughter, if their patients died. The descriptions of the symptoms and the treatment of various diseases still preserved in the works attributed to Hippocrates, are so striking for their good sense and acute observation, that the most competent judges consider them the foundation of all rational medicine in Europe. In all the larger Greek towns the art collections were always the main object of curiosity, which every one went to see. There were the temples either venerable for age, or remarkable for architectural splendor, and in them the statues of the gods, and the portraits of heroes and victors which were the work of famous sculptors. The inner walls of both temples and porticoes were often covered with frescoes, and had even separate pictures hung upon them. In fact, just as we now-a-days go to see in such a town as Antwerp or Rouen the churches, the pictures, the statues and carvings, and the antiquities, so every educated Greek enjoyed the arts, and thought his life incomplete without having seen their highest products. Crowds went to see the Pheidian statue of Zeus at Olympia, the Eros of Praxiteles at Thespiæ, the cow of Myron at Athens. Such great works were constantly copied, and to this practice we owe the inestimable benefit of finding in Roman galleries close imitations of the Greek masterpieces brought from Greece itself. Each important state was indeed represented in considerable cities by a proxenus, who corresponds to our modern consuls, but of course he could not be expected to offer hospitality to all travelers, though he did so to official visitors. Every distinguished family had accordingly family friends in foreign cities, to whom they were bound by mutual ties of hospitality. These friendships were handed down from generation to generation, and when the traveler had never seen his host he often brought with him a token formerly given to his family by the family he went to visit. On his arrival the host gave him a separate set of apartments, and supplied him with light, fuel and salt; he also sent him his dinner the first day, and invited him to dine afterward, but for the rest the guest was attended by his own servants, and supplied himself. As to the actual traveling, so much of it was done by sea that there seems to have been but indifferent means of journeying on land. To Delphi, Olympia, and such public resorts there were good roads, which could be traveled in carriages, but elsewhere pack mules and riding, or even walking was, as it now is, the only way of crossing the country.