“a matter of common report”

I have to quote this excerpt from the medieval guidebook to the prosecution of witches, Malleus Maleficarium. The author takes as a given that everybody knows about “those witches who … sometimes collect male organs [yes, penises] in great numbers, as many as twenty or thirty members together, and put them in a bird’s nest or shut them up in a box, where they move themselves like living members, and eat oats and corn, as has been seen by many and is a matter of common report[.]” (The ellipsis is in the original excerpt.)

source: Bonk: the curious coupling of science and sex by Mary Roach