I don't understand PageRank

My latest weblog El Canasto is a big success, with more and more readers every day. Every week a few other weblogs link to articles from El Canasto and therefore I expected my PageRank to increase, but to my big surprise Google decided to lower the PageRank for El Canasto last week. It went from 5 down to four, and I have no idea why.

Normally I wouldn't care about it, but in this case El Canasto was about to enter in the Top 500 of Spanish weblogs --and I expected an increase of visitors when arriving to that point-- but the PageRank is one of the factors used to calculate popularity. The decrease in PageRank set me back to position 650. I can only wait until I steadily grow again, or until Google makes another readjustment of the PageRank.

We depend too much on Google...