‘Quietly!’ Logan snorted.  ’I like “quietly.”  They would be on with the new love.  Don’t you see, you born gomeral, that the person, man or woman, who deserts the inconvenient A.—­I put an A. B. case—­falls in love with your agent B., and your B. is, by the nature of the thing, more ineligible than A.—­too poor.  A babe could see that.  You disappoint me, Merton.’

‘You state,’ said Merton, ’one of the practical difficulties which I foresaw.  Not that it does not suit us very well.  Our comrade and friend, man or woman, gets a chance of a good marriage, and, Logan, there is no better thing.  But parents and guardians would not stand much of that:  of people marrying our agents.’

‘Of course they wouldn’t.  Your idea is crazy.’

‘Wait a moment,’ said Merton.  ’The resources of science are not yet exhausted.  You have heard of the epoch-making discovery of Jenner, and its beneficent results in checking the ravages of smallpox, that scourge of the human race?’

‘Oh don’t talk like a printed book,’ Logan remonstrated.  ’Everybody has heard of vaccination.’

’And you are aware that similar prophylactic measures have been adopted, with more or less of success, in the case of other diseases?’

‘I am aware,’ said Logan, ’that you are in danger of personal suffering at my hands, as I already warned you.’

‘What is love but a disease?’ Merton asked dreamily.  ’A French savant, Monsieur Janet, says that nobody ever falls in love except when he is a little bit off colour:  I forget the French equivalent.’

‘I am coming for you,’ Logan arose in wrath.

’Sit down.  Well, your objection (which it did not need the eyes of an Argus to discover) is that the patients, the lovers young, whose loves are disapproved of by the family, will fall in love with our agents, insist on marrying them, and so the last state of these afflicted parents—­or children—­will be worse than the first.  Is that your objection?’

‘Of course it is; and crushing at that,’ Logan replied.

’Then science suggests prophylactic measures:  something akin to vaccination,’ Merton explained.  ’The agents must be warranted “immune.”  Nice new word!’

‘How?’

‘The object,’ Merton answered, ’is to make it impossible, or highly improbable, that our agents, after disentangling the affections of the patients, curing them of one attack, will accept their addresses, offered in a second fit of the fever.  In brief, the agents must not marry the patients, or not often.’

‘But how can you prevent them if they want to do it?’

’By a process akin, in the emotional region of our strangely blended nature, to inoculation.’

’Hanged if I understand you.  You keep on repeating yourself.  You dodder!’