It is certain, however, that the change of opinion itself has a tendency to separate men, even though the difference would not have made friendship impossible if it had existed from the first. Instances of this are often found in biographies, especially in religious biographies, because religious people are more “pained” and “wounded” by difference of opinion than others. We read in such books of the profound distress with which the hero found himself separated from his early friends by his new conviction on this or that point of theology. Political divergence produces the same effect in a minor degree, and with more of irritation than distress. Even divergence of opinion on artistic subjects is enough to produce coolness. Artists and men of letters become estranged from each other by modifications of their critical doctrines.

Differences of prosperity do not prevent the formation of friendship if they have existed previously, and can be taken as established facts; but if they widen afterwards they have a tendency to diminish it. They do so by altering the views of one of the parties about ways of living and about the multitude of things involving questions of expense. If the enriched man lives on a scale corresponding to his newly acquired wealth, he may be regarded by the other as pretentious beyond his station, whilst if he keeps to his old style he may be thought parsimonious. From delicacy he will cease to talk to the other about his money matters, which he spoke of with frankness when he was not so rich. If he has social ambition he will form new alliances with richer men, and the old friend may regard these with a little unconscious jealousy.

It has been observed that young artists often have a great esteem for the work of one of their number so long as its qualities are not recognized and rewarded by the public, but that so soon as the clever young man wins the natural meed of industry and ability his early friendships die. They were often the result of a generous indignation against public injustice, so when that injustice came to an end the kindness that was a protest against it ceased at the same time. In jealous natures it would no doubt be replaced by the conviction that public favor had rewarded merit far beyond its deserts.

In the political life of democracies we see men enthusiastically supported and really admired with sincerity so long as they remain in opposition, and their friends indulge the most favorable anticipations about what they would do if they came to power; but when they accept office they soon lose many of these friends, who are quite sure to be disappointed with the small degree in which their excessive hopes have been realized. There is no country where this is seen more frequently than in France, where Ministers are often criticised with the most unrelenting and uncharitable acerbity by the men and newspapers that helped to raise them.

Changes of physical constitution may be the death of friendship in this way. A friendship may be founded upon some sport that one of the parties becomes unable to follow. After that the two men cease to meet on the particularly pleasant occasions that every sport affords for its real votaries, and they only meet on common occasions, which are not the same because there is not the same jovial and hearty temper. In like manner a friendship may be weakened if one of the parties gives up some indulgence that both used to enjoy together. Many a friendship has been cemented by the habit of smoking, and weakened afterwards when one friend gave up the habit, declined the cigars that the other offered, and either did not accompany him to the smoking-room or sat there in open and vexatious nonconformity.

It is well known, so well known indeed as scarcely to require mention here, that one of the most frequent and powerful causes of the death of bachelor friendships is marriage. One of the two friends takes a wife, and the friendship is at once in peril. The maintenance of it depends upon the lady’s taste and temper. If not quite approved by her, it will languish for a little while and then die, in spite of all painful and visible efforts on the husband’s part to compensate, by extra attention, for the coolness of his wife. I have visited a Continental city where it is always understood that all bachelor friendships are broken off by marriage. This rule has at least the advantage of settling the question unequivocally.

Simple neglect is probably the most common of all causes deadly to friendship,—neglect arising either from real indifference, from constitutional indolence, or from excessive devotion to business. Friendly feelings must be either of extraordinary sincerity, or else strengthened by some extraneous motive of self-interest, to surmount petty inconveniences. The very slightest difficulty in maintaining intercourse is sufficient in most cases to insure its total cessation in a short time. Your house is somewhat difficult of access,—it is on a hill-side or at a little distance from a railway station: only the most sincere friends will be at the trouble to find you unless your rank is so high that it is a glory to visit you.

Poor friends often keep up intercourse with rich ones by sheer force of determination long after it ought to have been allowed to die its own natural death. When they do this without having the courage to require some approach to reciprocity they sink into the condition of mere clients, whom the patron may indeed treat with apparent kindness, but whom he regards with real indifference, taking no trouble whatever to maintain the old connection between them.

Equality of rank and fortune is not at all necessary to friendship, but a certain other kind of equality is. A real friendship can never be maintained unless there is an equal readiness on both sides to be at some pains and trouble for its maintenance; so if you perceive that a person whom you once supposed to be your friend will not put himself to any trouble on your account, the only course consistent with your dignity is to take exactly the same amount of pains to make yourself agreeable to him. After you have done this for a little time you will soon know if the friendship is really dead; for he is sure to perceive your neglect if he does not perceive his own, and he will either renew the intercourse with some empressement or else cease from it altogether.

In early life the right rule is to accept kindness gratefully from one’s elders and not to be sensitive about omissions, because such omissions are then often consistent with the most real and affectionate regard; but as a man advances towards middle-age it is right for him to be somewhat careful of his dignity and to require from friends, whatever may be their station, a certain general reciprocity. This should always be understood in rather a large sense, and not exacted in trifles. If he perceives that there is no reciprocity he cannot do better than drop an acquaintance that is but the phantom and simulacrum of Friendship’s living reality.