Is anything written by a Jew a Jewish text, and who decides?
What makes a text Jewish and how should we describe a library of Jewish texts? Rashi, a great Bible commentator, asked a similar question on the first verse of the Bible: "Why does the Bible start with the creation of the world and not with the laws given to the Jewish people?" For Rashi, the Bible was the source of Jewish law; other material was less important. Value judgments about the relative importance of different kinds of Jewish texts will inevitably affect what we label as Jewish texts.
Jewish texts begin with the Hebrew Bible, called Tanakh in Hebrew, and the language and idioms of the Bible serve as part of the "dialect" of much later Jewish literature. More directly, however, many later Jewish texts engage the laws and narratives of the Bible in conversation, through direct or indirect commentary. Some of these texts also use the structure of the Bible to provide their own basic structure. Much of the Zohar, the primary work of Jewish mysticism, is loosely organized around the weekly readings from the Torah, the first section of the Bible. Similarly, the Mishnah, the primary study-book for Jewish law, provides the structure for the Talmud and the hundreds of later commentaries on the Talmud.
A traditional way of dividing up the different literary elements of the Talmud has been the distinction of halakhah (law) and aggadah (legend or lore). Modern Jewish thinkers have extended these categories. For them, halakhah is anything that deals with Jewish behavior; aggadah is the meaning that underlies or is attributed to that behavior. These categories are most useful when one identifies their interactions. For example, the aggadah (meaning) of Sukkot (the autumn holiday in which Jews eat and often sleep in temporary huts) can include a sense of dependence when we are in an insecure home; that has brought about a new halakhah (behavior) for many Jews of making sure to make contributions to homeless shelters during the period prior to Sukkot.