**Negative
Numbers**

In 1759 the British mathematician Francis Maseres wrote that negative numbers "darken the very
whole doctrines of the equations and make dark of the things which are in their
nature excessively obvious and simple". Because of their dark and
mysterious nature, Maseres concluded that negative
numbers did not exist, as did his contemporary, William Friend. However, other
mathematicians were braver. They took a leap into the unknown and decided that
negative numbers could be used during calculations, as long as they had
disappeared upon reaching the solution.

The history of negative numbers is one of stops and starts.
The trailblazers were the Chinese who by 100 BC were able to solve simultaneous
equations involving negative numbers. The Ancient Greeks rejected negative
numbers as absurd, by 600 AD, the Indians had written the rules for the
multiplication of negative numbers and 400 years later, Arabic mathematicians
realised the importance of negative debt. But it wasn't until the Renaissance
that European mathematicians finally began to accept and use these perplexing
numbers.

http://www.bbc.co.uk/radio4/history/inourtime/inourtime_20060309.shtml