The Haggadah is rich also in allegorical speculation, of which there are traces in the Biblical books themselves. In the book of Micah, for example, we find that the patriarchs are taken as types of certain virtues, Abraham of Kindness, [Hebrew: hsd], and Jacob of Truth, [Hebrew: 'mt] (vii. 20). And when the ideas of the people expanded philosophically in Palestine and in Alexandria, the profounder conceptions were attached to Scripture by the device of allegorical interpretation, and certain rabbis attributed a higher value to the inner than to the literal meaning. Thus Akiba, who wrote an elaborate allegorical work upon the Song of Songs,[308] held that the book was the most profound in the Bible, and Rabbi Judah similarly regarded the book of Job.[309] The Palestinian allegorists took to themselves a wider field than the Alexandrian, and looked for the deeper meanings rather in the Wisdom Literature than in the Pentateuch, which was to them essentially the Book of the Law, and, therefore, not a fit subject for Mashal, _i.e._, inner meanings.[310] Hence, their allegorism was more natural, more real, and truer to the spirit of that which they interpreted. They allegorized when an allegory was invited, whereas Philo and his school often forced their philosophical meanings in face of the clear purport of the text, and without regard to the Hebrew. In the one case allegory was a genuine development, and might have been adopted by the original prophet: in the other, it was reconstruction; and the artificial un-Hebraic character of the Hellenistic commentary was one of the causes of its disappearance from Jewish tradition. While the Palestinian allegorists based their continuous philosophical interpretation upon the Wisdom Books, they, at the same time, looked for secondary meanings wherever opportunity offered, and found lessons in letters and teachings in names. An early school of commentators was actually known as [Hebrew: dorsh rshomot][311] or interpreters of signs, and their method was by examination of the letters of a word, or by comparison of different verses, to explore homilies. For instance, the verse, "And God showed Moses a tree" (Exod. xvi. 26), by which he sweetened the waters at Marah, symbolized, by a play on the word [Hebrew: vyvrhu],[312] that God taught Moses the Torah, of which it is said, "She is a tree of life" (Prov. iii. 18). Another happy example of this method occurs in the sixth section of the Pirke Abot, where the names in the itinerary, [Hebrew: mmtna nhlial, vmnhlial bmot] (Numb. xxi. 19), are invested with a spiritual meaning. Whoever believes in the Torah, it is written, shall be exalted, as it is said, "From the gift of the law man attains the heritage of God, and by that heritage he reaches Heaven."