What is the difference between politics and economics?

I think economics is simply a part of the greater subject of politics. For example, look at some of the political issues debated in the UK over the last few weeks: immigration, Gurkhas, Scottish independence, terrorism in Ulster. Although implicit to the root of these issues, economics didn't really come up in any of these debates.

One book that linked both [Politics and Economics] into one discipline is the book [B]Kautilya's Arthashastra[/B]. Going by the meaning of this word it must mean only Economics. But the book itself deals with Politics, Administartion and Economics amalgamated into one unit.