A 12th-century English natural philosopher and translator, Adelard of Bath trained at Tours and taught at Laon before a seven-year journey through southern Italy, Sicily, and possibly Cilicia, Syria, and Palestine. His most influential contribution was the first complete Latin version of Euclid's Elements from an Arabic version traditionally (with caution) attributed to Al-Hajjaj ibn Yusuf. He also translated al-Khwarizmi's astronomical tables, introducing Arabic numerals including zero to Europe, and wrote original dialogues including the Quaestiones Naturales.