Observing human judgement when responding to price is almost inverse to Economic's Law of Supply and Demand. If the price is relatively lower, people will tend to buy more items or in bulk. If it is more expensive, lesser quantity will be purchased. For the Law Supply and Demand, the independent or affecting factor is the demand or the quantity of goods and services purchased. The demands sets the market price of goods or services. The higher the demand, the higher the demand, the higher the market price is.
Hey we just read that too! How Mr. Frank says "no more" because he can't bare to remember his horrid past by reading his diary. In the first scene, he finds the diary and starts reading it. In scene 5, Mr. Frank finishes the book.
I think it's because they Africans were being robbed of their natural recourses so it is symbolic ever though you can't really steal a river I'm sorry if that doesn't make sense I hope it helped