with time tekhelet came to denote the color blue, the exact hue in antiquity is not definitively known. The task is made harder by the tendency of ancient writers to identify colors not so much by their hue, as by other factors such as luminosity, saturation and texture. Modern scholars believe that tekhelet probably referred to blue-purple and blue colors. The color of tekhelet was likely to have varied in practice, as ancient dyers were generally unable to reproduce exact colors from one batch of dye to another. Sources In the early classical sources (Septuagint, Aquila, Symmachus, Vulgate, Philo, and Josephus), tekhelet was translated into Greek as hyakinthos (, "hyacinth") or the Latin equivalent. The color of the hyacinth flower ranges from violet blue to a bluish purple (though the hyacinth species dominant in the eastern Mediterranean - Hyacinthus orientalis - is violet), and the word hyakinthos was used to describe both blue and purple colors. Early rabbinic sources provide indications as to the nature of the color. Some sources describe tekhelet as visually indistinguishable from indigo (kala ilan). This description is also somewhat ambiguous, as different varieties of indigo have colors ranging between blue and purple, but generally the color of dyed indigo in the ancient world was blue. Other rabbinic sources describe tekhelet as similar to the sea or sky. An oft-repeated explanation for the Torah's choice of tekhelet went as follows: "Why is tekhelet different from all other colors? Because tekhelet is similar [in appearance] to the sea, and the sea is similar to the sky, and the sky is similar to lapis lazuli, and lapis lazuli is similar to the Throne of Glory." (In a few versions of this source, "plants" (asavim) are included in this chain of similarity even though plants are not blue; though it has been suggested that these sources refer to bluish plants like hyacinth.) Jose ben Jose was another early author who described tekhelet as resembling the sky. In still other sources the color of tekhelet is compared to the night sky. Similarly, Rashi quotes Moshe ha-Darshan who describes it as "the color of the sky as it darkens toward evening" - a deep blue or dark violet. Rashi himself describes the color as "green" (ירוק) and "green, and close to the color of leeks", the latter commenting on a Talmudic passage according to which the morning Shema may be recited