When the Buddha contemplated the saṃsâra, the world of change and transmigration in which there is nothing permanent, nothing satisfying, nothing that can be called a self, he formulated his chief conclusions, theoretical and practical, in four propositions known as the four noble[435] truths, concerning suffering, the cause of suffering, the extinction of suffering, and the path to the extinction of suffering[436]. These truths are always represented as the essential and indispensable part of Buddhism. Without them, says the Buddha more than once, there can be no emancipation, and agreeably to this we find them represented as having formed part of the teaching of previous Buddhas[437] and consequently as being rediscovered rather than invented by Gotama. He even compares himself to one who has found in the jungle the site of an ancient city and caused it to be restored. It would therefore not be surprising if they were found in pre-Buddhist writings, and it has been pointed out that they are practically identical with the four divisions of the Hindu science of medicine: roga, disease; rogahetu, the cause of disease; arogya, absence of disease; bhaisajya, medicine. A similar parallel between the language of medicine and moral science can be found in the Yoga philosophy, and if the fourfold division of medicine can be shown to be anterior to Buddhism[438], it may well have suggested the mould in which the four truths were cast. The comparison of life and passion to disease is frequent in Buddhist writings and the Buddha is sometimes hailed as the King of Physicians. It is a just compendium of his doctrine—so far as an illustration can be a compendium—to say that human life is like a diseased body which requires to be cured by a proper regimen. But the Buddha's claim to originality is not thereby affected, for it rests upon just this, that he was able to regard life and religion in this spirit and to put aside the systems of ritual, speculation and self-mortification which were being preached all round him.