Currency relative values of the different currencies. Currencies in this sense are defined by governments, and each type has limited boundaries of acceptance. Other definitions of the term "currency" are discussed in their respective synonymous articles banknote, coin, and money. The latter definition, pertaining to the currency systems of nations, is the topic of this article. Currencies can be classified into two monetary systems: fiat money and commodity money, depending on what guarantees the value (the economy at large vs. the government's physical metal reserves). Some currencies are legal tender in certain political jurisdictions. Others are simply traded for their economic
What Is it Like to Be a Bat? perceptional experiences. While it is possible to imagine what it would be like to fly, navigate by sonar, hang upside down and eat insects like a bat, that is not the same as a bat's perspective. Nagel claims that even if humans were able to metamorphose gradually into bats, their brains would not have been wired as a bat's from birth; therefore, they would only be able to experience the life and behaviors of a bat, rather than the mindset. Such is the difference between subjective and objective points of view. According to Nagel, "our own mental activity is the