[Conditions of marriage. Indissoluble monogamy] The purpose of marriage once clearly understood, it becomes easy to define its conditions. The intervention of society is necessary; but its only object is to confirm and to develop the order of things which exists naturally. It is essential in the first place to the high purposes for which marriage has been instituted, that the union shall be both exclusive and indissoluble. So essential indeed are both conditions, that we frequently find them even when the connexion is illegal. That any one should have ventured to propound the doctrine that human happiness is to be secured by levity and inconsistency in love, is a fact which nothing but the utter deficiency of social and moral principles can explain. Love cannot be deep unless it remains constant to a fixed object. The very possibility of change is a temptation to it. So differently constituted as man and woman are, is their short life too much for perfect knowledge and love of one another? Yet the versatility to which most human affection is liable makes the intervention of society necessary. Without some check upon indecision and caprice, life might degenerate into a miserable series of experiments, each ending in failure and degradation. Sexual love may become a powerful engine for good: but only on the condition of placing it under rigorous and permanent discipline. Those who doubt the necessity for this, have only to cast a glance beyond Western Europe at the countries where no such discipline has been established. It has been said that the adoption or rejection of monogamy is a simple question of climate. But for this hypothesis there is no ground whatever. It is as contrary to common observation as to philosophic theory. Marriage, like every other human institution, has always been improving. Beginning in all countries with unrestricted polygamy, it tends in all to the purest monogamy. Tracing back the history of Northern Europe, we find polygamy there as well as in the South; and Southern nations, like Northern, adopt polygamy as their social life advances. We see the tendency to it in those parts of the East which come into contact with Western civilization.