摩訶止觀 9.9

9.9

四禪，世間本有，凡夫、外道共；專修此者祇發有漏。自行，十二門；化他，讚法讚者。《大經》云「所謂四十八年」，即此意也。

The four dhyānas exist originally in the mundane world and are shared by ordinary people and tīrthikas; one who exclusively cultivates them gives rise only to the tainted. In self-cultivation, they are the twelve gates; in transforming others, one praises the Dharma and praises the practitioner. When the Great Sūtra says, 'What is called forty-eight years,' this is precisely what it means.