until this time has evidently been becoming clearer and stronger? Again, people who are constitutionally tending to mental breakdown are very apt to load themselves down with duties and get themselves into situations which must necessarily prove to be too onerous and too perplexing for their poorly developed strength and skill. Of course, circumstances often require this. Many times, however, there is a kind of impulsive restlessness coupled with a short-sighted optimism, both constitutional, which, altogether more than ordinary circumstances, are to blame for undue assumption of work or care, and whose effect is, perhaps, best seen in the persistent tendency of such people to originate and perpetuate exhausting habits, both of mind and body. Thus, the habit of self-poisoning from poorly digested and poorly assimilated food is easily acquired by such people, and always becomes a source of progressive brain starvation and often of consequent mental breakdown. Says Dr. A. S. Thayer (Journal of Medicine and Science, vol. iii, page 173), "There is ground for belief that exhaustion—fatigue—is dependent upon poisoning of the cells of the brain, muscles, and other tissues by the waste products of functional activity."[1] Again, as already noted, perversions of the natural instincts—of appetite for food, of desire for gain, of social or other ambitions, and especially of the sexual impulse and its habitual indulgence—fasten themselves upon such individuals with a permanence and destructiveness that must almost of necessity lead to disaster.[2] And so we may see that as a most natural, although often a far-removed, result of unphysiological marriages, proceeding through generations which have been thus predestinated to weakening choices and practices, insanity finally appears to mark the ultimate extent both of the mental disorganization and bodily inefficiency, which extent is owing not only to the original initiating steps, but also to subsequent stages of causation, progressively developed from generation to generation.
Another great source of vitiation of the stream of tendency is found in two people who marry in a truly enough physiological sense, but who find or force themselves in lives of wear and tear which progressively unfit them for childbearing and child nurture. Poorly calculated ambitions, unexpected difficulties to be surmounted, depressing oppositions, with perhaps more or less actual disease or accident, largely account for this in a general way. Obviously, during the child-rearing age, the effect of what parents are obliged to endure and execute upon the fortunes of progeny becomes a matter of far-reaching importance. That anything which persistently exhausts or overstrains the parents must tell in the later dynamic tendency and
