A while ago I discussed the Bunuel film where different actresses play the same character, and I discussed later how we try to identify people by their faces, or by the sound of their voice. Dogs do the same by their sense of smell, perhaps.
The difference between the film and reality is that Bunuel signifies the identity by convention. The actresses don’t look that alike, certainly not as identical twins look alike. But Bunuel uses cinematic conventions to convey the identity. One actress is seen opening the door, the other is seen walking through the other side. With actual perception the identity is signified naturally.
Before printing, we identified proper names in the same way. Here are two tokens of the word 'Plato' in Worcester 13 9rb and 11vb. With electronic printing, we are used to the same word looking exactly the same, which is guaranteed by the computer representing the five letters in the name 'Plato' by the ASCII characters 80, 108, 97, 116 and 111 respectively. This is what allows us to search an electronic document for the same name, or perform a Google search for ‘Plato’.
Even printing on paper guarantees that the letters will look nearly the same.
Before that, we recognised proper names just as we recognised faces.