What is the theme in Reminiscences of a Stock Operator by Edwin Lefevre?

One of Livingston's favorite admonitions to traders is that they should not speculate on the basis of tips, no matter how trustworthy the source seems to be. He suggests most tips are generated by insiders who are using them to manipulate the market to their own ends. Livingston tells many tales of foolish traders who chase tips and also bemoans the fate of the general public, whom he believes is the most hurt by them.