The 'four meditation heavens' in the realm of form. The four spheres one is born into depending upon one's level of meditation practice in the four meditative concentrations 四禅. There are various sources which describe these， but one of the most extensive is the Abhidharmako/sa-bha^sya 俱舍论， where they are discussed in connection with the term 四静虑; the Zen gaku jiten cites a text called the Jietuodao lun 解脱道论. Those who practice the first meditative concentration in the present lifetime are born in the first meditation heaven into one of three different levels according to their proficiency in practice. Those of the lower level are born into heaven of Brahma followers 梵众天; those of middling level are born into the heaven of Brahma's ministers 梵辅天 and those of the superior level are born into the great Brahma heaven 大梵天. In similar fashion， those who practice the second meditation in the present life are born into three grades of heavens according to their proficiency in practice: the heaven of limited light 少光天; the heaven of limitless light 无量光天 and the heaven of ultimate light and purity 极光净天. In the third heaven there are again three: the heaven of limited purity 少净天， the heaven of limitless purity 无量净天 and the heaven of pervasive purity 遍净天. The fourth heaven has eight levels: the first three of these， the cloudless heaven 无云天 the heaven of blessed birth 福生天 and the heaven of extensive fruition 广果天 are attainable by unenlightened sentient beings; the final five are attained only by Buddhist saints who have consummated the undefiled concentration of the fourth level: these are the heaven of no affliction 无烦天， the heaven of no heat 无热天， the heaven of skillful manifestation 善现天， the heaven of skillful vision 善见天， and the heaven of ultimate form 色究竟天. ［俱舍论、 T 1558.29.41a］