Charak Samhita
वक्ष्यन्ते कारणान्यष्टौ स्मृतिर्यैरुपजायते। निमित्तरूपग्रहणात् सादृश्यात् सविपर्ययात् ॥१४८॥
The following are the eight factors that bring about a good memory: 1. Knowledge of cause (of a thing and event etc.); 2. Knowledge of form (e.g. after seeing gavaya in the forest one remembers a cow having a similar form); 3. Knowledge of similarity (e.g. on seeing a son one remembers his father having similar form);
english translation
vakSyante kAraNAnyaSTau smRtiryairupajAyate। nimittarUpagrahaNAt sAdRzyAt saviparyayAt ॥148॥
hk transliteration by Sanscript