 By and large, these three roads lead to very different areas, with correspondingly divergent histories, of which no unified account can be expected. (However, in the Dialectica Interpretation, as proposed and understood by Gödel [1958, 1970, 1972], they came close to one another.)  Following the main theme of the present account, our topic will remain the intuitionistic meaning explanation of logic. But a number of early highlights of the formal turn are presented in this supplementary document: