The Compendium of Caraka 4.1.147

4.1.147

smṛtiḥ satsevanādyaiśca dhṛtyantairupajāyate/
smṛtvā svabhāvaṃ bhāvānāṃ smaran duḥkhāt pramucyate
vakṣyante kāraṇānyaṣṭau smṛtiryairupajāyate/
nimittarūpagrahaṇāt sādṛśyāt saviparyayāt//

Memory is produced by service of the virtuous and the rest, ending with steadfastness; / having recalled the intrinsic nature of things, one who remembers is freed from suffering. / The eight causes through which memory is produced will be stated: / from apprehension of a cause or form, from similarity, from contrast,