What is exactly causing the current worldwide depression?

[Kagemusha]

I would like to hear opinions of the esteemed Orgahs, about the reasons behind the current depression, which is threatening the global economy? Is it caused by sloppy credit giving by banks and investment banks? Or is it just a normal phenomenom of hitting a economical low point, which is followed by high tide? Or maybe something else? For example all the economy papers were hinting for many months before the credit crisis that investors should move their funds from stocks, into gold for example.
Was this an event where we can wittness vice analyst´s predicting the future downfal of markets, or was this an intentional manouver from investors to create a downfal in stock values? Since it is natural phenomenom that once people who are playing with lend money are forced to sell because of lack of ability to pay, or lack of more credit, prizes go down and others who have access for large amounts of funds can buy many things for extraordinary cheap prizes.

In the end is it even possible for investors to speculate on such grand scale?Opinions and thoughts please, if you will.