Economic theory, in every branch, deals with practical affairs. Its subject is human welfare, and it is never entirely dissociated from the practical question of how human welfare is to be promoted. But it is a special characteristic of the art of central banking that it deals specifically with the task of an authority directly entrusted with the promotion of human welfare. Human welfare, human motives, human behaviour supply material so baffling and elusive that many people are sceptical of the possibility of building a scientific edifice on so shifting a foundation. But however complex the material, and however imperfect the data, there is always an advantage to be gained from systematic thought.

Preface - The Art of Central Banking (1932)