"One, which I mention several times elsewhere, is the need for patience if big profits are to be made from investment. Put another way, it is often easier to tell what will happen to the price of a stock than how much time will elapse before it happens. The other is the inherently deceptive nature of the stock market. Doing what everybody else is doing at the moment, and therefore what you have an almost irresistible urge to do, is often the wrong thing to do at all."

Next Quote

To make our position clearer, we may formulate it in another way. Let us call a proposition which records an actual or possible observation an experiential proposition. Then we may say that it is the mark of a genuine factual proposition, not that it should be equivalent to an experiential proposition, or any finite number of experiential propositions, but simply that some experiential propositions can be deduced from it in conjunction with certain other premises without being deducible from those other premises alone.

— A.J. Ayer