Some say that the world has evolved since creation, as it is the law of nature to evolve. And others say the reverse, seeing the conditions of the world falling back every day. When the Buddhists say that the universe is always progressing, the Hindus contradict this by pointing out that virtue and truth have been diminishing with the growth of the world, during the periods called Satya Yuga, Treta Yuga, Dvapara Yuga and the present Kali Yuga, the golden silver, copper and iron ages.