“Only,” he answered, “in the case of the insane.  When the doctors are satisfied that a lunatic cannot be cured, an inquest is held; and if the medical verdict be approved, he is quietly and painlessly dismissed from existence.  Logically, of course, the same principle should be applied to all incurable disease; and I suspect—­indeed I know—­that it is applied when the household have become weary, and the patient is utterly unable to protect himself or appeal to the law.  But the general application of the principle has been successfully resisted, on the ground that the terror it would cause, the constant anxiety and alarm in which men would live if the right of judging when life had become worthless to them were left to others, would far outweigh any benefit which might be derived from the legalised extinction of existences which had become a prolonged misery; and such cases, as I have told you, are very rare among us.  A case of hopeless bodily suffering, not terminating very speedily in death, does not occur thrice a year among the whole population of the planet, except through accident.  We have means of curing at the outset almost all of those diseases which the observance for hundreds of generations of sound physical conditions of life has not extirpated; and in the worst instances our anaesthetics seldom fail to extinguish the sense of pain without impairing intellect.  Of course, any one who is tired of his life is at liberty to put an end to it, and any one else may assist him.  But, though the clinging to existence is perhaps the most irrational of all those purely animal instincts on emancipation from which we pride ourselves, it is the strongest and the most lasting.  The life of most of my countrymen would be to me intolerable weariness, if only from the utter want, after wealth is attained, of all warmer and less isolated interest than some one pet scientific pursuit can afford; and yet more from the total absence of affection, family duties, and the various mental occupations which interest in others affords.  But though the question whether life is worth living has long ago been settled among us in the negative, suicide, the logical outcome of that conviction, is the rarest of all the methods by which life is terminated.”

“Which seems to show that even in Mars logic does not always dominate life and prevail over instinct.  But what is the most usual cause of death, where neither disease nor senility are other than rare exceptions?”

“Efflux of time,” Esmo replied with an ironical smile.  “That is the chief fatal disease recognised by our physicians.”

“And what is its nature?”

“Ah, that neither I nor any other physician can tell you.  Life ’goes out,’ like a lamp when the materials supplying the electric current are exhausted; and yet here all the waste of which physic can take cognisance is fully repaired, and the circuit is not broken.”

“What are the symptoms, then?”