From: Bryan Levman
Message: 4700
Date: 2016-09-05
"sabbāva sañjānanalakkhaṇā, tadevetanti puna sañjānanapaccayanimittakaraṇarasā dāruādīsu tacchakādayo viya, yathāgahitanimittavasena abhinivesakaraṇapaccupaṭṭhānā hatthidassakāndhā (udā. 54) viya, yathāupaṭṭhitavisayapadaṭṭhānā tiṇapurisakesu migapotakānaṃ purisāti uppannasaññā viyāti."
"All (saññā) has the characteristic of recognition (sañjānana); its property is the making of representation (nimitta) that is a condition of recognizing again, 'this is the very same thing' - as carpenters and so on do with the wood, etc.; its manifestation is the producing of conviction by virtue of a representation (nimitta) that has been accordingly learnt - like the blind perceiving the elephant ( http://www.accesstoinsight.org/tipitaka ... .than.html ); its basis is whatever object that has come near - like the recognition (saññā) 'people' that arises for young animals in respect of scarecrows."
The term “sign” renders the Pāli word nimitta. A nimitta is a sign in the sense that it can refer to the outward characteristic mark of things. These characteristics are the signs, the sign-als, that make it possible to recognize things.
...
In relation to the process of perception in general, the nimitta is what causes one to recognize something. An illustrative example for this function of the nimitta can be gathered from a situation depicted in the Raṭṭhapāla-sutta. Raṭṭhapāla had gone forth against the wish of his parents. After a long time had passed, he decided to visit his home town. Having arrived there, he approached his parental house while begging for alms. Seeing him from afar, his father did not recognize him and started abusing him, expressing his resentment towards these shaven-headed recluses who he felt had lured his only son away from him. Raṭṭhapāla turned around and left.
Here the father had not been able to recognize the characteristic marks, nimitta, of his own son, probably because he had never seen him dressed as a monk and with shaven head. In addition to the different outer attire, Raṭṭhapāla would also have been walking in a more self-restrained manner than earlier, when he was still living at home. All these differences, combined with the fact that the father only saw the monk from afar, would have made recognition difficult.
The story does not end here. A female servant left the house to throw away some stale food. Raṭṭhapāla approached her and asked that she give the food to him, instead of throwing it away. On coming close to Raṭṭhapāla to do that, the female servant recognized that this monk was the son of the head of her household. The Raṭṭhapāla-sutta and one of its parallels preserved in the Madhyama-āgama agree in using the term nimitta (and its Chinese equivalent) in this context, specifying that she recognized Raṭṭhapāla by the nimitta of his hands and feet, as well as by the nimitta of his voice.34
This shows the functioning of a nimitta as a central factor in the operational mechanics of memory and recognition. It is with the help of the nimitta that the perception aggregate is able to match information received through the senses with concepts, ideas, and memories.
"Atha kho āyasmato raṭṭhapālassa ñātidāsī taṃ ābhidosikaṃ kummāsaṃ āyasmato raṭṭhapālassa patte ākirantī hatthānañca pādānañca sarassa ca nimittaṃ aggahesi."
... While she was doing so, she recognised the characteristic features of his hands, his feet, and his voice.
https://suttacentral.net/en/mn82
"While a slavewoman belonging to one of venerable Raṭṭhapāla's relatives was pouring some old porridge into venerable Raṭṭhapāla's bowl, she apprehended (gaṇhāti) her inner representation (nimitta) of his hands, his feet, and his voice."
'ehi tvaṃ bhikkhu, indriyesu guttadvāro hohi, cakkhunā rūpaṃ disvā mā nimittaggāhī hohi mānubyañjanaggāhī..."
(MN 107 and other suttas)