The fourth and last Dhyāna is also called Samādhi, and properly means such a perfect concentration of the soul’s faculties, that the soul becomes merged in itself. It is often used to denote an ecstatic condition, scarcely to be distinguished from trance or hypnotism or catalepsy. Those devotees in India who practise it are buried, not burnt, and their tombs are called Samādhs. To return now to Buddhist Cosmology, the theory of later Buddhism is that he who has practised the first Dhyāna will rise at death to one of the three tiers of heavens connected with that first Dhyāna, i.e. to the first and lowest of the four groups of worlds of true form (rūpa), in which all sexual distinctions are obliterated. This first or lowest group consists of the worlds of the Brahmās, a high order of gods divided into three classes with three tiers of abodes. The first class of Brahmā gods, inhabiting the first or lowest of the tiers of the Brahmā abodes, consists of the Brahma-parisajjā devāḥ, or beings who constitute the retinue of the god Mahā-brahmā—the chief of all the Buddhist gods. The second class of Brahmā gods, inhabiting the second tier, consists of the Brahma-purohitā devāḥ, ‘beings who are the ministers of Mahā-brahmā.’ The third class of Brahmā gods, inhabiting the highest of the three tiers, consists of the Mahā-brahmās, ‘great Brahmās,’ of whom Mahā-brahmā is the chief. The inhabitants of these three worlds are sometimes called the Brahma-kāyikā devāḥ, ‘gods having a Brahmā form.’ It is important, however, to note that Brahmā or Mahā-brahmā, sometimes called Brahmā Sahām-pati, ‘lord of those who have to suffer[100],’ is the king of _all_ the higher heavens (p. 214), ruling there, as Mara and Indra do in the lower worlds and heavens of sense and desire. Out of deference to Brāhmanism he has been adopted as the chief god of the Buddhist Pantheon, and yet he is far inferior to the Buddha. Furthermore, it is to be observed that every Ćakra-vāla or ‘system of worlds’ (see p. 120) has its own Mahā-brahmā ruling over its own higher heavens, and that as there are countless Ćakra-vāla, so there are countless Mahā-brahmās. Nor is any of these chief gods eternal. Each has to pass into some other form of existence at the end of vast periods of time, and is then succeeded by another. Gautama Buddha himself was born four times as Mahā-brahmā (see p. 111). The second group of worlds of true form has also three tiers of heavens like the first, and is assigned as an abode to those who have risen to the second degree of contemplation. The characteristic of these three heavens is that they are regions of true light—not of the sun’s light, but of mental enlightenment, and each of the three is inhabited by beings who have raised themselves to different heights of knowledge and intelligence.