Fairly sure the answer is: It allowed people to buy and sell goods in a wider market.
Think about it: without coins, people had to barter with mostly short-term goods, but coins held value over time and most people would accept it as payment. However, if you had to use, say, carrots, the guy you're trying to buy lettuce from may not need/want carrots, but he can use those coins to buy what he DOES need.
Hope I helped!
Feudalism allowed large territories to be governed in the absence of a central government. Each lord or vassal raised an army to defend his fief and to serve the king as needed. One drawback to this system was that the nobles were very powerful because they controlled the armies.
Voting rights, I would say.
Galen's area of expertise were in pharmacology, surgery and anatomy. He was also known by the name of "father of experimental physiology". He was not only a biologist but also a physician. He was born in 129 AD and died on 219 AD. He was very famous for making the first experimental medicine.
