Why did Sensex crash from 20K to under 10K?

http://economictimes.indiatimes.com/rssarticleshow/msid-3901597,flstry-1.cms

A voice of sanity. Its amazing how sentimental we become when it comes to making our decisions. Like the author says here:

“It is strange that when prices fall in general, we are all happy because goods are now better value. But when stock prices fall, we shed copious tears. Exactly the same stocks with exactly the same economic fundamentals were great buys with Sensex at 20,000; but they are bad investments today with Sensex at some 10000 odd!”

On the whole though a good time to buy.