Any one who has just taken a certain quantity of food of a certain kind will not immediately have the same strength of desire for another similar quantity. Within any single period of want every additional act of satisfaction will be estimated less highly than a preceding one obtained from a quantity of goods equal in kind and amount.
Many material wants are not intermittent, but require a continuous satisfaction. Such for instance is the need of warmth, the human body requiring to be kept at a certain temperature.
Here also Gossen's law applies. That action which is needed to secure the required minimum temperature, -- that is, the expenditure for clothing, fuel, and so on, indispensable for keeping the body in sufficient warmth, -- will be most intensely desired, while the multiplication of this necessary expenditure does not affect our well-being in the same degree, and will be much less eagerly desired. In the long run the prospect of any further increase will be met with aversion.
With regard to the higher wants, -- those which come into existence whenever the necessaries of life are secured, -- the same law obtains. It is not, however, so noticeable to ordinary observation, and, indeed, appearances are rather against it. The wants of wealth appear to be the very opposite to those of poverty. The latter are urgent but narrowly limited; the former can be done without, but, when awakened, show themselves many-sided and extensive. Many-sided, because they are from the first rich in varieties, and become always more so, as one gives rise to another; and extensive, because they frequently include objects of great compass, increasing with the degree of culture attained. On this account it might well be thought that such wants were infinite and subject to no diminution. But on looking more closely at the matter we shall find that, when the same act of enjoyment is repeated without variation, -- the very same, and neither extended nor changed,the result is in this case also weariness and disgust. The thirst of a collector seems to be insatiable, and his object certainly is one of extraordinary compass, even though it be confined to one article. The man who collects books or pictures requires a great fortune, and may not even then be able to fully satisfy his wish. Every new book he acquires serves to stimulate instead of to weaken his desire, and this is not due to morbid extravagance: it is entirely justifiable, as it brings him nearer to his object, the possession of a perfect library or a perfect picture gallery.
But how would it be, if he were offered a duplicate of some work he already had? This and this alone, as Gossen remarked, would be a case of exact repetition, -- of the repeated satisfaction of the same impulse; and here, without doubt, the desire would be much lessened, probably entirely destroyed. And thus we shall ever find it to be if we direct our attention strictly to the proper object. Even desires such as that of power or of wisdom, even ambition, greed of honour, thirst for knowledge are not exempt from the same rule. The sum of what these crave, when at their height, is infinite; no man's life or strength is sufficient to satisfy them wholly even once, not to speak of repeating it. But the single acts which make up this whole sum, the individual effects, exercises of power, acquisitions of knowledge can be repeated and tired of. The charm of the whole lies in the power to vary the items. Nothing on earth is of such a nature that man can go on enjoying it over and over again, and lose himself in its contemplation. This holds of all emotions, from hunger to love.
