안녕하세요 ^^, When the creditors started to collect on the money that was outstanding from borrowers the amount of money in the supply decreased. According to Mr. Fisher's theory this was the "primary"cause(likely among others but in his theory the main cause) of the great depression. 2) On a side note there are many theorized causes of what triggered the great depression. One is the Stock Market Crash of 1929. Another is that Banks were not insured at the time, and the willingness to borrow money to consumers was not there for the banks. Also environmentally the USA was in what was called the dust bowl at the time. It was a big mix of a lot of factors that caused the Great Depression to happen as well. If you would like to watch an interesting documentary about the recent recession that occurred in the USA in the 2000's you may want to view "Inside Job" very interesting and Matt Damon narrates! 좋은 하루 보내세요!

Susan is correct. It appears part of the sentence is missing the function word "of". " Irving Fisher attributed the primary cause of the Great Depression to the fact that money was being transferred from borrowers to creditors, which decreased the money supply in the market. All it is saying is the supply of money in the economy was reduced because creditors(banks) were not lending money resulting in corporations and people not having money to purchase new products or equipment. It is part of monetary theory.

The transfer of money from borrowers to creditors decreased the money supply. The primary cause means the main cause.