§ 42
In a consideration of the essential factors in a happy marriage we are dealing primarily with the most fundamental of the instincts. For all practical purposes it is sufficient to distinguish broadly the two main groups of instincts that are associated with the ideas of love and of ego.
In popular language we are inclined to say that whatever one does without conscious forethought is instinctive, yet on further consideration it appears that unplanned, impulsive acts or groups of acts may, according to one’s bringing up, be habitual acts. These are acquired, not innate acts, and yet as soon as any mode of behaviour becomes habitual or automatic, the acts constituting it, occurring without forethought or conscious control, are as unpremeditated as is any instinctive act. One needs, then, to be careful not to consider as instinctive what is merely habitual.
Habits, because they are imposed upon the mind and body from without, and therefore are not innate and original, may be more easily changed than instincts. Yet it is quite evident that man has to control his instincts as well as to form habits. In spite of the greater difficulty of changing the acts which gratify the instinctive desires, this change can be made.
Asceticism and abstinence both prove that the sex instincts can be given a different expression, and that a permanent, if not always deep, mental satisfaction can come from the formation of ascetic habits. But the effect of these, however spectacular it may be in the accomplishment of egoistic or social ends, is always a bad one on the body.
Indeed, this bad effect on the body was even desired by the early religious ascetics who thought that by mortifying the flesh (making the body as dead as possible), they could immortalize the soul or mind; a view which modern science has shown to be erroneous, dependent as it is on merely verbal reasoning.