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I'm trying to remember a book I read in the mid to late 90's (but which I think was written in the 60's or 70's) in which the hero was a spy that got captured by his rivals, blinded and put in a prison. There he somehow manages to build a device that allows him to see what nearby animals can see, with a dial to select between animals. He uses this to attempt an escape.
I don't remember much else except that the planet that captured him had a strict Lutherian communist economic structure in which the local currency was something like 'an hour', representing precisely the amount of time you worked to get that amount.
Anyone remember the author and title of this book? I never owned a copy. I lived in a shared house at the time and I no longer have contact with the house mate that leant me his copy to read.