At some time in your life you have been on a river in a canoe and hopefully you had a paddle. You know about being up the creek without one.
You quickly learned that paddling up stream is much harder than paddling down stream. The lesson of going with the flow can be applied to many aspects of life and especially to the stock market. In the creek it is easy to know which way the current is flowing, but in the market it is much more difficult. At least that is what Wall Street wants you to think.
On the river there are markers and navigations buoys to help you with your passage, but in the money world there are few such true indicators. Actually it is very easy to determine the flow of funds in the market. Standing on the shore are people (brokers) shouting to go to the right and another next to him screaming to go to the left.