"We need have no reason to follow the rule as we do. The chain of reasons has an end."

Wittgenstein notes here that if we need rules to help us interpret general systems of signs like writing and numbers, then we must also need rules to interpret these rules, and further rules to interpret this second set of rules, and so on. For instance, if in writing down the series of cardinal numbers you need to refer mentally to the rule "Add one" in order to write the next number in the sequence, you must also mentally refer to the rule that tells you how to interpret the rule "Add one." Wittgenstein shows us that providing general rules is not an end-all explanation for how to proceed. Rather, we simply behave the way we do out of convention.