We maintain that there is only one basis upon which successful speculation can be carried on continually; that is, never to buy a security unless it is selling at a price below that which is warranted by assets, earning power, and prospective future earning power.
There are many influences that affect the movements of stock prices, which are referred to in subsequent chapters. All of these should be studied and understood, but they should be used as secondary factors in relation to the value of the stock in which you are trading.