One thing, however, it is necessary to emphasise. If any symptom of this sort--and the remark applies especially to headaches--is found consistently to come on during the hours of work, alleviating after the work is over for the day, it should be taken as a danger signal. For when anyone’s occupation brings on a headache, the complaint is much more likely to be due to some weakness of the nervous system than to any fault in digestion or eyesight. And the same applies to many other symptoms also. The phenomena I am about to describe are those suggestive of nervous weakness, and any man or woman who recognises themselves in the picture I shall attempt to draw had better take warning. They need not alarm themselves unduly, but they will be well advised to pull up short. There is one point which must always be kept in mind. It does not follow that because a person is easily tired, or is irritable or depressed or dreads any ordeal awaiting him, or is nervous in any direction, that he or she is drifting towards a breakdown. It is when people who have previously been free from such weaknesses find that they are acquiring them that they must face the fact their nervous systems are on the down grade. Each individual must be taken as his or her own standard. What is natural for some would be unnatural for others. A person is ill when he falls below his own level of health, either of body or mind. The various signs of neurasthenia or breakdown depend, not on comparing a man with anyone else, but in measuring him by his former self. [Sidenote: Loss of strength.] One of the most constant symptoms is a gradual decline in strength, either of body or mind, without any organic disease to account for it. If a man whose heart, lungs and kidneys have been proved sound begins to suffer from fatigue after an amount of exercise such as he would not previously have noticed, everything points to the fact of its being the result of some impairment in his nervous system. More particularly so if the tiredness is of an unpleasant nature. There is a delightful form of fatigue and there is a painful one. There is nothing more enjoyable than the gentle aching which a healthy man feels as he stretches out his limbs in a comfortable chair after a good day’s walking, shooting, golf or whatever else it may have been. He feels, in mind and body alike, a delicious sense of half-sleepy lassitude, which affords to a higher degree than anything else a sense of repose and well-being. That is very different from the weariness that dogs a man’s footsteps wherever he goes, or is even with him during his sleeping hours, so that he rises in the morning more tired than when he lay down. When that happens something in his organisation has gone wrong.