and the seventh of Eliezer ben Jose HaGelili. This may be described as argument by analogy, which infers from the similarity of two cases that the legal decision given for the one holds good for the other also. The term gezerah shavah originally included arguments based on analogies either in word or in fact. Before long, however, the latter class was designated as hekkesh, while the phrase gezerah shavah was limited to analogy in the case of two different Biblical laws containing a word common to both. The gezerah shavah was originally restricted to a δὶς λεγόμενον (dis legomenon), i.e., a word occurring only in the two passages offering the analogy. Since such a word is found nowhere else, there is no reason to assume that it bears different meanings in the two passages. The gezerah shavah consequently attaches to the word in the one passage the entire sequence of ideas which it bears in the other. Such a gezerah shavah is purely lexicographical, as seeking to determine the exact signification of a word by comparison with another passage in which the full meaning of such word is clear. The rule thus demonstrates itself. For example: The phrase ("to wring off the head") occurs only twice in the Pentateuch (Leviticus 1:15, 5:8). In 5:8, however, the meaning of the phrase is more closely defined by ("from the neck"). The Sifra concludes, therefore, that the elaboration "from the neck" (in 5:8) is part of the concept of the word , and consequently that מלק means "to wring the head from the neck" in 1:15 also. In order to use this principle, one must first have a prior knowledge or notion about a certain thing (premise), from whence he wishes to apply the same notion or premise to something else that is currently unknown to him. In the Babylonian Talmud (Pesahim 66a), Hillel the elder made use of an argument by analogy when he wanted to show that it was permitted for a man to do labor on the Sabbath day when preparing his Passover offering on the eve of the Jewish holiday. Hillel observed that in two biblical verses appeared the words, "at its appointed time" (), the one in , for which there is some prior knowledge about its practice, viz. "Command the children of Israel... my [daily whole-burnt] offering...shall ye observe to offer unto me at its appointed time"