We have seen in the above story that some of those who valiantly endeavoured to gain the new lake perished by the way, and so we find that our recent scientific advances have been a cause of nerve-trouble, apart from the persecutions they have entailed. The mental strife we have gone through in our attempt to reconcile the ideas stored in our minds, by no will of our own, with God’s ever-progressive revelation, should teach us not to instil into the minds of our children as absolute truth that which must necessarily be but approximate truth, changing always with our own development. Seeming scientific facts themselves assume a different complexion so soon as scientific discovery goes still further. Even the axiom that two straight lines continued to infinity cannot meet, ceases to be a fact to us, and is relegated to the region of rational hypothesis, when we realise that we have never so much as seen a straight line, all seeming straight lines being but parts of curves; and that the mental picture we have been accustomed to form of a straight line is but a picture of one of these curving lines. Almost the hardest thing we have to learn is the impiety of putting cherished beliefs in the place of the great God of the universe. Like Abraham, we are called upon to sacrifice our Isaac. Like Abraham, we no sooner freely consent to do so, than we find the ram ready for the sacrifice. Directly we close our eyes to God’s progressive revelation and accustom ourselves to inconsistency and to fallacious reasoning, we unconsciously deteriorate. Another outcome of recent rapid changes has been a great increase of wealth, together with its unequal distribution. Whether this unequal distribution might have been prevented, and whether it may or may not now be remedied, cannot here be discussed. We have but to inquire whether it has anything to do with the prevalent nerve-trouble; and I think we must admit that excessive luxury on the one hand, and excessive poverty on the other, are largely productive both of monotony and overwork. At all events, it is principally amongst the well-to-do classes that _ennui_ is complained of. It cannot be doubted that monotony is a fertile source of nervous disease. The fact is not always received, because the nature of the evil is not understood. We fail to realise that monotony is an actual strain upon the nerves, often an even greater strain than extreme fatigue; for those who are overworked are supposed to require a holiday or change of occupation, while those who are suffering from monotony often get no relief until so much harm is done that mere change of scene or of occupation is inadequate to repair the damage done to the ill-treated nerves. In such cases the mischief wrought in the individual is similar to the mischief now being wrought in the community--in each there is excessive use of one part and disuse of another.