A sailor and his dog, the sole survivors from a wreck, have been tossing on a raft for many days. Land is in sight, but still far away, and the food is reduced to a couple of biscuits. Both man and dog are equally famished, and it becomes evident that, unless each gets a biscuit, one of them will not live to reach the shore. Here we are confronted with the opposing claims of two wants, that of the sailor and that of his dog; and, as the sailor is, presumably, the valuer, the two wants are of very different importance to him. The question is, What measures the value of the biscuits? According to our formula, the answer will be found by ascertaining which is the dependent want—which is the satisfaction that the biscuits condition. At first sight, one would say that the actual destination of the biscuits determined this; but that would be to say that two exactly similar biscuits, both available to the one man, and available under exactly similar conditions, were of different value. In this dilemma, one little consideration easily determines the point. If one of the biscuits were lost, which want would go unsatisfied? For the want which is satisfied if the good is present, and unsatisfied if it is not, is evidently the dependent want.[10] [10] There are two typical cases where valuations are made:—where a man values something he _has_, with the view of parting with it (in selling, giving, lending, etc.), and where he values something he _has not_, with the view of acquiring it. As will be seen from above, the two methods of valuation come practically to the same result. The dependent want, in this case, is that of the dog; that is, it is the _less important_ of the two wants. To put it now in more general terms. As we saw, the (necessarily) limited resources at each man’s disposal, he, consciously or unconsciously, apportions out among his various wants according to his particular scale, taking care that the more urgent ones are provided for before the less urgent. It is obvious that, in these circumstances, there is a _least_ want that is satisfied, although ordinarily we are not conscious what it is. But it immediately comes to the front when, from any cause, our resources are diminished. If a working man’s wage is reduced from twenty shillings to nineteen shillings a week, he becomes painfully conscious that some want, hitherto satisfied, must go bare, and the particular want on which he economises immediately points out which was his least, or least urgent, or final want. In this case, all the wants previously satisfied are still satisfied except the last one, and it is proved that none of them depended on having or losing the shilling. Again, all wants under this, just as before, remain unsatisfied whether the shilling is there or not. Only this marginal want is satisfied if the shilling is present and unsatisfied if absent: it alone, then, is the dependent want.