Epicurus divides the needs of mankind into three classes, and the division made by this great professor of happiness is a true and a fine one.  First come natural and necessary needs, such as, when not satisfied, produce pain,—­food and clothing, victus et amictus, needs which can easily be satisfied.  Secondly, there are those needs which, though natural, are not necessary, such as the gratification of certain of the senses.  I may add, however, that in the report given by Diogenes Laertius, Epicurus does not mention which of the senses he means; so that on this point my account of his doctrine is somewhat more definite and exact than the original.  These are needs rather more difficult to satisfy.  The third class consists of needs which are neither natural nor necessary, the need of luxury and prodigality, show and splendor, which never come to an end, and are very hard to satisfy.[1]

[Footnote 1:  Cf.  Diogenes Laertius, Bk. x., ch. xxvii., pp. 127 and 149; also Cicero de finibus, i., 13.]

It is difficult, if not impossible, to define the limits which reason should impose on the desire for wealth; for there is no absolute or definite amount of wealth which will satisfy a man.  The amount is always relative, that is to say, just so much as will maintain the proportion between what he wants and what he gets; for to measure a man’s happiness only by what he gets, and not also by what he expects to get, is as futile as to try and express a fraction which shall have a numerator but no denominator.  A man never feels the loss of things which it never occurs to him to ask for; he is just as happy without them; whilst another, who may have a hundred times as much, feels miserable because he has not got the one thing he wants.  In fact, here too, every man has an horizon of his own, and he will expect as much as he thinks it is possible for him to get.  If an object within his horizon looks as though he could confidently reckon on getting it, he is happy; but if difficulties come in the way, he is miserable.  What lies beyond his horizon has no effect at all upon him.  So it is that the vast possessions of the rich do not agitate the poor, and conversely, that a wealthy man is not consoled by all his wealth for the failure of his hopes.  Riches, one may say, are like sea-water; the more you drink the thirstier you become; and the same is true of fame.  The loss of wealth and prosperity leaves a man, as soon as the first pangs of grief are over, in very much the same habitual temper as before; and the reason of this is, that as soon as fate diminishes the amount of his possessions, he himself immediately reduces the amount of his claims.  But when misfortune comes upon us, to reduce the amount of our claims is just what is most painful; once that we have done so, the pain becomes less and less, and is felt no more; like an old wound which has healed.  Conversely, when a piece of good fortune befalls us, our claims