The Arthashastra then posits its own theory that there are four necessary fields of knowledge, the Vedas, the "Anvikshaki" (philosophy of "Samkhya", "Yoga" and "Lokayata"), the science of government and the science of economics ("Varta" of agriculture, cattle and trade). It is from these four that all other knowledge, wealth and human prosperity is derived. The Kautilya text thereafter asserts that it is the Vedas that discuss what is Dharma (right, moral, ethical) and what is Adharma (wrong, immoral, unethical), it is the "Varta" that explain what creates wealth and what destroys wealth, it is the science of government that illuminates what is "Nyaya" (justice, expedient, proper) and "Anyaya" (unjust, inexpedient, improper), and that it is "Anvishaki" (philosophy) that is the light of these sciences, as well as the source of all knowledge, the guide to virtues, and the means to all kinds of acts. He says of government in general: