And Al-Khwarizmi is a Persian mathematician and physicist, and he's famous for being the father of algebra. The word algebra that we now have today, and the subject that you can learn a lot about on Khan Academy, it comes from the Arabic word al-jabr, and his book, Al-Kitab Al-Muqtasar Fi Hissab Al-Jabr Wal-Muqabla, which literally means, and those of you who might speak Arabic, or Persian, or even Hindi or Urdu might recognize Kitab is book, and then Hissab is calculation, and al-jabr is an operation of completion, and it's essentially, it's one of the operations we now do in algebra, where you're doing the same thing to both sides of the equation, and balancing, it was also a very similar operation. He also brought the Indian number system, or the Hindu numerals, he brought them to the Islamic empire, and that was really the bridge to bringing it to the West. Famously, Pope Sylvester II, he was educated in Catalonia with the point of acquiring knowledge that was gained from the Arabs. Remember, the Arabs were in control, or the Islamic empires, it was not the Abbasids, it was actually the remnants of the Umayyads were in control of Spain at the time, but because of that, this area was considered a center of learning, and Pope Sylvester, who got his education there, he's the one that is often given credit for being one of the first to introduce the decimal numeral system, this Hindu-Arabic decimal system that we now use for our numeric system, as opposed to something like Roman numerals. Well, another very interesting thing is not only the word algebra comes from algebra, but the word algorithm literally comes from his name, the name al-Khwarizmi, al-Khwarizmi in Latin, they pronounce as algorithmi. So other significant contributors to the science of all of human civilization are people like al-Marwazi.