§86

Wittgenstein asks us to imagine the language game of §2 (the block/slab language) but with a chart. A gives B written signs ('block', 'slab') and B looks up the signs in a chart and finds a corresponding picture of a shape of a building stone.

B learns to look up the picture in the chart through training - by passing his finger from left to right (from sign to picture).

You could draw in arrows (to explain how you are to pass from sign to picture). But the chart was not incomplete without this schema of arrows.

Wittgenstein has been making several points in these passages - (i) rules can be misinterpreted (ii) we can introduce new rules/new explanations to 'reinforce' the existing rules but these, in turn, can be misinterpreted (iii) however, what can be misinterpreted can also be interpreted correctly (iv) - so there need be no infinite regress of rules to achieve perfect clarity (v) we introduce rules/explanations as we need them/to suit our purposes - if they have served their purpose then there need not be 'back-up' (vi) language does not need to be everywhere bounded by rules (vii) we need not follow definite rules in every utterance that we make (viii) it is possible that what we say might be vague (and not analysable then into a disjunction of elements with determinate meaning).