Well, who could fail to be intrigued by a posting entitled "Ivan Illich and Silence as a Commons"? Especially when it links to an essay called "Silence is a Commons" by said Illich (dating back to 1983), with the following definition of a commons:
People called commons those parts of the environment for which customary law exacted specific forms of community respect. People called commons that part of the environment which lay beyond their own thresholds and outside of their own possessions, to which, however, they had recognized claims of usage, not to produce commodities but to provide for the subsistence of their households. The customary law which humanized the environment by establishing the commons was usually unwritten. It was unwritten law not only because people did not care to write it down, but because what it protected was a reality much too complex to fit into paragraphs. The law of the commons regulates the right of way, the right to fish and to hunt, to graze, and to collect wood or medicinal plants in the forest.
An oak tree might be in the commons. Its shade, in summer, is reserved for the shepherd and his flock; its acorns are reserved for the pigs of the neighbouring peasants; its dry branches serve as fuel for the widows of the village; some of its fresh twigs in springtime are cut as ornaments for the church - and at sunset it might be the place for the village assembly. When people spoke about commons ... they designated an aspect of the environment that was limited, that was necessary for the community's survival, that was necessary for different groups in different ways, but which, in a strictly economic sense, was not perceived as scarce.