In some of the papers on the concept of library of Masakazu Nakai (1900-1952), a library is defined as ‘a storehouse of the memory of a nation’. Nakai proposed two concepts of media, that is, ‘medium’ and ‘mittel’.

‘Medium’ is agency or medium in which senders of communications have an advantage over recievers, while ‘mittel’ is agency or medium in which senders and recievers are equal. Within the two, memory belongs to ‘medium’.

His theory of library is famous for its slogan that we should transform a substantial library into functional library, that is, a library without walls, books and buildings. This functional library corresponds to ‘mittel’, while library as ‘a storehouse of the memory of a nation’ relates to ‘medium’, because memory belongs to ‘medium’.

In Nakai's theory, do libraries belong to ‘medium’ or ‘mittel’?

This article attributes this confusion to the complexity of his concept of memory. In ordinary meaning, memory is accompanied by oblivion, and, in a limited sense, memory is memory without a lapse, that is, exhaustive records. Memory with oblivion leads to consistent theories and, finally, results in books. On the other hand, memory without lapse, goes beyond the framework of a book, or a library, and moves toward becoming a database system.

This consideration of ‘medium’ as exhaustive records requires us to regard a secretariat as an opposite concept of a committee. This article understands ‘medium’ as exhaustive records, which a secretariat owns and controls, a fulcrum of a committee, which makes resolute decisions through ‘mittel’. In this context, we can realize the relationship between ‘mittel’ and ‘medium’, or the meaning of ‘mittel’ with the support of ‘medium’.