In some places there are serpents of two cubits in length, with membraneous wings like bats. They fly at night, and let fall drops of urine or sweat, which occasions the skin of persons [CAS. 703] who are not on their guard to putrefy. There are also winged scorpions of great size. Ebony grows there. There are also dogs of great courage, which do not loose their hold till water is poured into their nostrils: some of them destroy their sight, and the eyes of others even fall out, by the eagerness of their bite. Both a lion and a bull were held fast by one of these dogs. The bull was caught by the muzzle, and died before the dog could be loosened. 38. In the mountainous country is a river, the Silas, on the surface of which nothing will float. Democritus, who had travelled over a large part of Asia, disbelieves this, and Aristotle does not credit it, although atmospheres exist so rare that no bird can sustain its flight in them. Vapours also, which ascend (from some substances), attract and absorb, as it were, whatever is flying over them; as amber attracts straw, and the magnet iron, and perhaps there may be in water a similar power. As these matters belong to physics and to the question of floating bodies, these must be referred to them. At present we must proceed to what follows, and to the subjects more nearly relating to geography. 39. It is said that the Indians are divided into seven castes. The first in rank, but the smallest in number, are the philosophers. Persons who intend to offer sacrifice, or to perform any sacred rite, have the services of these persons on their private account; but the kings employ them in a public capacity at the time of the Great Assembly, as it is called, where at the beginning of the new year all the philosophers repair to the king at the gate, and anything useful which they have committed to writing, or observed, tending to improve the productions of the earth or animals, or of advantage to the government of the state, is then publicly declared. Whoever has been detected in giving false information thrice is enjoined silence by law during the rest of his life; but he who has made correct observations is exempted from all contributions and tribute. 40. The second caste is that of husbandmen, who constitute the majority of natives, and are a most mild and gentle people, as they are exempted from military service, and cultivate their land free from alarm; they do not resort to cities, either to transact private business, or take part in public tumults. It therefore frequently happens that at the same time, and in the same part of the country, one body of men are in battle array, and engaged in contests with the enemy, while others are ploughing or digging in security, having these soldiers to protect them. The whole of the territory belongs to the king. They cultivate it on the terms of receiving as wages a fourth part of the produce.