A problem with the Hindu system is that it was written backwards. So, the number thirty-two would be written as 23.

Jewish intellectuals frequently served as the translators--translating Arabic into Hebrew for themselves and then into Spanish for the Christians.

Despite these, the scholarly tradition of the Greeks was preserved in Alexandria and at the university at Jundishahpur (Persia), where excommunicated Nestorian Christian scholars went in 431 and some Greek scholars found refuge after Plato's Academy was closed in 529.

The ability to magnetize iron by placing it near a loadstone was known to ancient civilizations.

By the end of this period, both artillery and the cavalry were playing a large role in battle.

This military manual also gave directions for making a bomb using gunpowder so most historians believe that bombs or grenades were used by Chinese troops from before the 11th century.

Each of these materials had its own production and most of them required the contributions of more than one individual. Manufacturing techniques remained unchanged over a long period of time. To produce wool, the fleece needed to be washed and then combed to remove tangles. Next, the yarn needed to be spun with a spindle. Here is a description of this process

"Iron is one of the most useful metals ever discovered, but it is also one of the more difficult metals to understand in history, especially in medieval history. Iron comes in several forms, and the complications involved in producing each of them fosters further confusion."

With the clock, time became divided into regulated units instead of remaining dependent on events or the day.

"Practical science...has been important from the first, and has continually increased in importance, until it has almost ousted theoretical science from men's thoughts...The triumph of science has been mainly due to its practical utility, and there has been an attempt to divorce this aspect from that of theory, thus making science more a technique, and less and less a doctrine as to the nature of the world....science as technique was building up in practical men a quite different outlook from any that was to be found among theoretical philosophers.  Technique confers a sense of power: man is much less at the mercy of his environment than he was in former times."