The king said: ‘In how many ways, Nāgasena, does memory spring up?’
‘In sixteen ways, O king. That is to say: by personal experience, as when the venerable Ānanda, or the devoted woman Khujjuttarā, or any others who had that power, called to mind their previous births— or by outward aid, as when others continue to remind one who is by nature forgetful—or by the impression made by the greatness of some occasion, as kings remember their coronation day, or as we remember the day of our conversion-by the impression made by joy, as when one remembers that which gave him pleasure—or by the impression made by sorrow, as when one remembers that which pained him—or from similarity of appearance, as on seeing one like them we call to mind the mother or father or sister or brother, or on seeing a camel or an ox or an ass we call to mind others like them—or by difference of appearance, as when we remember that such and such a colour, sound, smell, taste, or touch belong to such and such a thing—or by the knowledge of speech, as when one who is by nature forgetful is reminded by others and then himself remembers—or by a sign, as when we recognise a draught bullock by a brand mark or some other sign-or from effort to recollect as when one by nature forgetful is made to recollect by being urged again and again: “try and think of it"—or by calculation, as when one knows by the training he has received in writing that such and such a letter ought to follow after such and such a one—or by arithmetic, as when accountants do big sums by their knowledge of figures—or by learning by heart, as the repeaters of the scriptures by their skill in learning by heart recollect so much— or by meditation, as when a Bhikkhu calls to mind his temporary states in days gone by—by reference to a book, as when kings calling to mind a previous regulation, say: “Bring the book here,” and remind themselves out of that—or by a pledge, as when at the sight of goods deposited a man recollects (the circumstances under which they were pledged)—or by association, as when one remembers a thing because one has seen it, or a sound because one has heard it, or an odour because one has smelt it, or a touch because one has felt it, or a concept because one has perceived it.’
‘Very good, Nāgasena!’