§51

What does 'R's signifying a red square consist in? - NOT that people, when they are describing squares, always say 'R' when there is a red square - because someone might go wrong in their description - they might make a mistake. - Is this parallel to the point that the meaning of a word is not how it is, in fact, always used - but it's correct use?

It needn't be that people using the language always have a red square come before their mind when they say 'R'. - Meaning 'red square' by 'R' then does not consist in having some particular thing before one's mind.