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- [Instructor] In other videos we talk about the rapid spread of Islam, and one of the interesting things about these early Islamic empires is they preserved much of what they inherited from the Byzantine and the Persian empires. The infrastructure including the roads, the bureaucracy. A lot of the culture. And they also began to collect the knowledge from within the empire and from the peoples that they encountered on the borders of the empire including the Indians, and the Chinese. And they did this throughout the Umayyad dynasty. But it really came to its full fruition during the Abbasid Caliphate. Now the Abbasid Caliphate, one of the first things they did under the Calph al-Mansur is build Baghdad and move the capital of the empire to Baghdad. Now one of al-Mansur's successors al-Rashid, is famous for making Baghdad a center of learning. According to the historian John William Draper this is a sense of what life was like under al-Rashid's rule. During the period of the Calphs the learned men of the Christians and the Jews were not only held in great esteem, but were appointed to posts of great responsibilities and were promoted to the higher ranking jobs in the government. He, Calph Haroon Rasheed, never considered to which country alerted person belonged nor his faith in belief but only his excellence in the field of learning. And to get a sense of how much learning and how advanced the knowledge began to be especially under the rulership of al-Rashid, during this time he was a contemporary of Charlemagne who was the Frankish king. He was also the first holy Roman emperor. And so it's this region right over here. And they were trading gifts and this is a historical account Haroon al-Rashid sends Charlemagne this water clock. And it's so foreign to the Francs to Charlemagne, that he thinks that it's it must be some type of magic. That it can't be explained by just normal means. And then things really get invested in terms of collecting knowledge as we get into the rule of al-Rashid's son al-Ma'mun where he creates in Baghdad what is called The House of Wisdom. Which is this center of learning, of mathematics, astronomy, physics, medicine, geography, and map making, poetry, philosophy. And, over the next several hundred years these Abbasid Caliphs are going to sponsor scholars from India, learn it in Sanskrit and the ancient Sanskrit text in Greek, Chinese, Persian to translate as much of the knowledge and to collect it in libraries in cities, like Baghdad. To translate it into Arabic, and to collect all of that knowledge in one place. And just to get a sense of the type of advances that occurred during this golden age of Islam which correlates strongly, or is essentially during the Abbasid dynasty and it ends with the Mongol invasion in the middle of the 13th century right over here. There are scientists like Al-Kwarizmi. And Al-Kwarizmi is a Persian mathematician and physicist. And he's famous for being the father of algebra. The word algebra that we now have today the subject you can learn a lot about on Khan Academy it comes from the Arabic word al-jabr and his book al-Kitab al-mukhtasar fi hisab al-jabr wal-muqabala which literally means, and those of you who might speak Arabic, or Persian, or even Hindi or who might recognize Kitab as book. And then hisab 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 Balancing is 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 the second he was educated in Catalonia with the point of acquiring knowledge that was gained from the Arabs. Remember, the Arabs were in control over the Islamic empires. It was not the Abbasids it was actually the remnants of the Umayyads who 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 al-jabr but the word algorithm is literally comes from his name. The name Al-Kwarizmi, Al-Kwarizmi in Latin they pronounce as algarithme. So other significant contributors to the science of all of human civilization are people like al-Marwazi. Al-Marwazi, once again, in Baghdad. And he would have been a contemporary of al-Kwarizmi. And he, if you've ever taken trigonometry, or if you're about to take trigonometry, he is accredited with coming up with the core trigonometric functions. We're talking about sine, cosine. Tangent and cotangent it might have been Marwazi or it might have been another mathematician named al-Buzjani who came a little bit after, or a lot depending on a human scale, but was also based in Baghdad. And together, they came up with the six the six trigonometric functions. They weren't contemporaries of each other but they both made significant contributions to what we now call trigonometry. Including many of the trigonometric identities that we now learn in high school. Now you also have physicists, mathematicians, astronomers, like Alhazon. And he is credited as getting one of the more sophisticated views of how light and vision works. These are some quotes from Alhazon. From each point of every color body illuminated by any light issue light and color along every straight line that can be drawn from that point. This is a fairly sophisticated view of how light actually works. And he's also credited with using and understanding the scientific method several hundred years before the Renaissance in Europe. The duty of a man, the duty of the man who investigates the writing of scientists. If learning the truth is his goal is to make himself an enemy of all that he reads and attack it from every side. He should also suspect himself as he performs his critical examination of it so that he may avoid falling into either prejudice or leniency. And now another very famous poet philosopher mathematician poly math of the time was Omar Khayyan. And in the west, he's most famous for his poetry. Most famously the work of the Rubaiyat the translation by Fitzgerald. But he was also a significant philosopher mathematician. This is a picture of some of his work right over here. You can see that he did his work in the 11th and the 12th centuries. And he did it from (mumbling). But he investigated Pascal's Triangle and the binomial theorem. And keep in mind, this was over 500 years before Pascal. So maybe it should actually be called Khayyam's Triangle. And just to get a sense of his poetry, or a sense of the (mumbling) in general, which I encourage you to look up and read. And this is at least Fitzgerald's translation of it. And that inverted bowl we call the sky where under crawling cooped we live and die. Lift not they hands to it for help for it rolls impotently on as thou or I. So as you can imagine, this Islamic world these empires between the eighth and 13th centuries, it was actually a very powerful bridge of human knowledge taking knowledge from the Indians, the Chinese, the Ancient Greeks, and providing a bridge during the Dark Ages in Europe. And get a sense of that, we have some text from some historians on that time period. This is some text from this is some text from the historian Phillip Hiti. And he wrote, During all the first part of the Middle Ages no other people made as important a contribution to human progress as did the Arabs. If we take this term to mean all those whose mother tongue was Arabic and not merely those living in the Arabian peninsula. For centuries, Arabic was a language of learning, culture, and intellectual progress for the whole of the civilized world with the exception of the Far East. From the ninth to the 12th century, there were more philosophical medical historical religious astronomical and geographical works written in Arabic than in any other human tongue. And we also have a frame, a point of view from Bertrand Russell in his History of Western Philosophy who wrote, Our use of the phrase the Dark Ages to cover the period from 699 to 1000 marks our undue concentration on Western Europe. In China, this period includes the time of the Tang dynasty, the greatest age of Chinese poetry. From India to Spain, the brilliant civilization of Islam flourished. What was lost to Christendom at this time was not lost to civilization, but quite the contrary. To us it seems that Western European civilization is civilization, but this is a narrow view.