My summer reading has included two remarkable books that build bridges to the world of the ancient Israelites.

The starting point for “The Rarest Blue: The Remarkable Story of an Ancient Color Lost to History and Rediscovered” by Baruch Sterman and Judy Taubes Sterman is Numbers 15:37-38, in which God tells Moses, “Speak to the children of Israel, and instruct them to make for themselves fringes on the corners of their garments throughout the ages; let them attach a thread of blue to the fringe at each corner.”

Most readers will recognize the first part of this commandment as tzitzit — the fringes affixed to the prayer shawls worn during prayer, as well as to garments worn every day by many observant Jews. If the part about the thread of blue does not ring a bell, that’s quite understandable.

The Hebrew word for “blue” used in the text is tekhelet, which the ancient rabbis identified as a color derived exclusively from a particular sea mollusk, the hilazon. By the time the Talmud was codified, the ability to create this dye had been lost, and fulfillment of this commandment would remain dormant for more than a millennium. As is lamented in the ancient collection Midrash Rabbah, “And now we have only white, for tekhelet has been hidden.”

Tekhelet was a source of longing over the centuries, and never exited the Jewish consciousness (for example, it was the inspiration for the blue in the Israeli flag). In the 19th century, the Hassidic rebbe of Radzyn, who was a trained biologist, devoted himself to rediscovering the lost dye. Research led him to believe that the hilazon was a cuttlefish, and he began producing threads dyed through an elaborate process that began with the creature’s ink.

In the early 20th century, Rabbi Isaac Herzog, who would later become the first Ashkenazi chief rabbi of Israel, concluded that the Radzyner rebbe had erred. Drawing on a discovery by a French zoologist, Herzog came to believe that the source of tekhelet was the hypobranchial gland of the Murex trunculus snail. However, Herzog’s experiments with the snail resulted in a dye that was purple, rather than blue. It was not until the 1980s that a group of Israelis intent on solving the riddle of tekhelet discovered that exposing secretions from the gland to sunlight would result in the rich blue described in ancient Jewish texts. Although some controversy remains, it is now a practice among many observant Jews to adorn their tzitzit with a thread of blue derived from the Murex trunculus.

“The Rarest Blue” is a fascinating combination of detective story, history lesson and scientific explanation. Much of the science comes in its exploration of the color itself. The special status of blue in many cultures (think “royal blue” and “blue ribbon”) is tied to the scarcity of the color in the natural world. The book goes into detail about why this is the case, explicating the conditions necessary for the color blue to be perceived (which is entirely different for the blue of the sky, of the sea and of dyed fabric).

Considering that Baruch Sterman is a major figure in the revival of tekhelet, the book has surprisingly little discussion of religious thought and practice. However, one of the few explicit religious statements struck me as profound and worth sharing: Because of the rarity and expense of blue dye in antiquity, the color generally was restricted to the wealthy and powerful (including Israel’s priestly caste). The Torah’s mandate that all men wear strands of tekhelet conveys what the authors call “the epitome of the democratic thrust within Judaism, which equalizes not by leveling, but by elevating: All of Israel is enjoined to become a nation of priests.”

Hebrew University biblical scholars Avigdor Shinan and Yair Zakovitch employ a different sort of detective work in “From Gods to God: How the Bible Debunked, Suppressed, or Changed Ancient Myths and Legends.” Incorporating close textual analysis, scholarship on the ancient Near East and exhaustive knowledge of classical midrash, they argue convincingly that the Hebrew Bible preserves its editors’ efforts to reshape pre-existing stories in order to impose a theological and political framework that would replace the variant practices, oral traditions and beliefs (including polytheism) that existed among the ancient Israelites.

The example I’ll cite here is the birth of Moses, which is related in Exodus 2:1 as follows: “A certain man of the house of Levi went and married a Levite woman. The woman conceived and bore a son.” Where most religious traditions give their major figures elaborate birth stories (think of a certain birth many centuries later in Bethlehem, for example), the minimalism here is conspicuous.

Shinan and Zakovitch point out, however, that the midrashic tradition is full of miraculous stories of Moses’ birth — for example, that he was selected by the Lord in the womb and was born circumcised; and that his mother was 130 years old, and her pregnancy was short and the childbirth painless. They argue that these stories were not later elaborations of the Torah’s simple account but, rather, a reflection of an older tradition that had been deliberately suppressed during the Bible’s formation. They hold that the biblical editors excised these wonder tales to prevent a cult from developing around Moses, blurring the “distinction between the message bearer and the message sender.”

Approachable and illuminating, the book enriches our understanding of both the biblical text and the environment in which it emerged.

“The Rarest Blue: The Remarkable Story of an Ancient Color Lost to History and Rediscovered” by Baruch Sterman and Judy Taubes Sterman (320 pages, Lyons Press, $24.95)

“From Gods to God: How the Bible Debunked, Suppressed, or Changed Ancient Myths and Legends” by Avigdor Shinan and Yair Zakovitch (320 pages, Jewish Publication Society, $27.95)

Howard Freedman is the director of the Jewish Community Library, a program of Jewish LearningWorks, in San Francisco. All books mentioned in this column may be borrowed from the library.