The Baraita of the Forty-nine Rules (Hebrew: ברייתא מ"ט מדות) is a work of rabbinical literature which is no longer in existence except in references by later authorities.
[2] Zunz showed, by referring to a number of passages in the Talmud, that the tanna R. Nathan, in both halakhah and aggadah, was accustomed to group things arithmetically, and to arrange his sayings accordingly.
[5] If from these short fragments an opinion could be formed concerning the composition of the Baraita, Zunz's assumption would be justified that it contained aggadah and halakhah numerically arranged.
Mishnat ha-Middot has nothing in common with the Baraita cited by the old scholars under that name: for the citations leave no doubt that the Baraita, even in its mathematical parts, was founded on the Bible; whereas the Mishnat ha-Middot is a purely secular work, and, possibly, it drew upon the same source as did Mohammed b. Musa, the oldest Arabic mathematician.
The argument that the Mishnat ha-Middot has not been preserved in its entirety, and that in its original form there were references to the Bible for special points, is of no weight, since it is absolutely incomprehensible that aggadic or halakhic matter should fit into the frame of the work as it now is.