In the medieval Islamic world the Arabic word (i.e., astrolabe) was given various etymologies. In Arabic texts, the word is translated as (, lit. "star-taker"), a direct translation of the Greek word. Al-Biruni quotes and criticises medieval scientist Hamza al-Isfahani who stated: "asturlab is an arabisation of this Persian phrase" (, meaning "taker of the stars"). In medieval Islamic sources, there is also a folk etymology of the word as "lines of lab", where "Lab" refers to a certain son of Idris (Enoch). This etymology is mentioned by a 10th-century scientist named al-Qummi but rejected by al-Khwarizmi. History Ancient world An early astrolabe was invented in the Hellenistic civilization by Apollonius of Perga between 220 and 150 BC, often attributed to Hipparchus. The astrolabe was a marriage of the planisphere and dioptra, effectively an analog calculator capable of working out several different kinds of problems in astronomy. Theon of Alexandria ( – ) wrote a detailed treatise on the astrolabe, and Lewis argues that Ptolemy used an astrolabe to make the astronomical observations recorded in the Tetrabiblos. The invention of the plane astrolabe is sometimes wrongly attributed to Theon's daughter Hypatia (; died 415 AD), but it is, in fact, known to have already been in use at least 500 years before Hypatia was born. The misattribution comes from a misinterpretation of a statement in a letter written by Hypatia's pupil Synesius ( – ), which mentions that Hypatia had taught him how to construct a plane astrolabe, but does not state anything about her having invented it herself. Astrolabes continued in use in the Greek-speaking world throughout the Byzantine period. About 550 AD, Christian philosopher John Philoponus wrote a treatise on the astrolabe in Greek, which is the earliest extant treatise on the instrument. Mesopotamian bishop Severus Sebokht also wrote a treatise on the astrolabe in the Syriac language in the mid-7th century. Sebokht refers to the astrolabe as being made of brass in the introduction of his treatise, indicating that metal astrolabes were known in the Christian East well before they were developed in the Islamic world or in the Latin West. The first Renaissance treatises dealing with scientific problems were based on earlier classical works and were often concerned with Ptolemaic doctrines. Medieval era Astrolabes were further developed in the medieval Islamic world, where Muslim astronomers introduced angular scales to the design, adding circles indicating azimuths on