The five qualities above enumerated are present in different degrees in every investment, and the scientific investor naturally selects those securities which possess in a high degree the qualities upon which he wishes to place emphasis. A large part of the problem of investment lies in the careful selection of securities to meet one's actual requirements. The average investor does not thoroughly understand this point. He does not realize that a high degree of one quality involves a lower degree of other qualities. He may have a general impression that a high rate of income is apt to indicate less assurance of safety, but he rarely applies the same reasoning to other qualities. When he buys securities, he is quite likely to pay for qualities which he does not need. It is very common, for example, when he wishes to make a permanent investment and has no thought of reselling, to find him purchasing securities which possess in a high degree the quality of convertibility. From his point of view, this is pure waste. A high degree of convertibility is only obtained at the sacrifice of some other quality--usually rate of income. If he were to use more care in his selections, he could probably find some other security possessing equal safety, equal stability, and equal promise of appreciation in value, which would yield considerably greater revenue, lacking only ready convertibility. Thus he would satisfy his real requirements and obtain a greater income, at the expense only of a quality which he does not need. The quality of convertibility divides investors into classes more sharply than any other quality. For some investors convertibility is a matter of small importance; for others it is the paramount consideration. Generally speaking, the private investor does not need to place much emphasis upon the quality of convertibility, at least for the larger part of his estate. On the other hand, for a business surplus, ready convertibility is an absolute necessity, and in order to secure it, something in the way of income must usually be sacrificed.