It is really reather surprising that things like this can get "lost."
I wonder how and why it happens.
To go back further in time it is amazing that a "lost" piece of music by such as Mozart, or Haydn can be found. It would be awful if they were gone for ever.

I think that with the advent of sound, interest in silent films rapidly fell away, and in those days there was little interest in the idea of the preservation of silent films. In those days film was on nitrate which tended to deteriorate. Of course it is only in modern times with the advent of VHS that the idea of finding old films became more popular.

Although this find above is important it is overshadowed by the finding of a more complete version of Metropolis by Fritz Lang. It is doubtful whether the original full version exists but this version is around 25 minutes longer than the generally available version. It was premiered a few days ago in the States and this is a link to a review of this more complete version.

Fascinating - as is the review to which you linked, conveying the merits of the film in its own right, and also its place in the history of cinema.Thank you.