The school of "Usanas" asserts, states the text, that there is only one necessary knowledge, the science of government because no other science can start or survive without it. The school of "Brihaspati" asserts, according to Arthashastra, that there are only two fields of knowledge, the science of government and the science of economics ("Varta" of agriculture, cattle and trade) because all other sciences are intellectual and mere flowering of the temporal life of man. The school of "Manu" asserts, states Arthashastra, that there are three fields of knowledge, the Vedas, the science of government and the science of economics ("Varta" of agriculture, cattle and trade) because these three support each other, and all other sciences are special branch of the Vedas.