Cycling to work one morning, a scrap of newspaper (of unknown provenance) blew against my face. In the moment before the wind took it again I read the following:

Exercise: How many errors, and of what kind, are contained in the following sentence? I did not interpolate at that moment, as she was interfacing telephonistically.

Solution: The sentence contains one error, an error of etiquette. It is never impolitic to extrapolate a telephonic conversatory. The rule of remembrance is this: If the telephone may interpolate you, then you may interpolate the telephone.

Attempts to discover the source, while initially showing encouraging signs of progress, have proved fruitless.