This article of Al Fârâbi, the Arabic text of which has recently been edited together with its English and Turkish translations,is not mentioned by our biographic and bibliographic sources prior to the thirteenth century. In addition, although Ibn abi Uşaybi`a, one of our thirteenth century sources, mentions it, there is no reference to it in Ibn al Kifti, another important thirteenth century source. Moreover, among later bibliographic sources, Şafadi seems to be the only one speaking of it. Haji Khalifa, e. g, does not seem to have seen it.