And, finally, there is always the prospect of a new disease.  As yet science has scarcely touched more than the fringe of the probabilities associated with the minute fungi that constitute our zymotic diseases.  But the bacilli have no more settled down into their final quiescence than have men; like ourselves, they are adapting themselves to new conditions and acquiring new powers.  The plagues of the Middle Ages, for instance, seem to have been begotten of a strange bacillus engendered under conditions that sanitary science, in spite of its panacea of drainage, still admits are imperfectly understood, and for all we know even now we may be quite unwittingly evolving some new and more terrible plague—­a plague that will not take ten or twenty or thirty per cent., as plagues have done in the past, but the entire hundred.

No; man’s complacent assumption of the future is too confident.  We think, because things have been easy for mankind as a whole for a generation or so, we are going on to perfect comfort and security in the future.  We think that we shall always go to work at ten and leave off at four, and have dinner at seven for ever and ever.  But these four suggestions, out of a host of others, must surely do a little against this complacency.  Even now, for all we can tell, the coming terror may be crouching for its spring and the fall of humanity be at hand.  In the case of every other predominant animal the world has ever seen, I repeat, the hour of its complete ascendency has been the eve of its entire overthrow.  But if some poor story-writing man ventures to figure this sober probability in a tale, not a reviewer in London but will tell him his theme is the utterly impossible.  And, when the thing happens, one may doubt if even then one will get the recognition one deserves.

THE WRITING OF ESSAYS

The art of the essayist is so simple, so entirely free from canons of criticism, and withal so delightful, that one must needs wonder why all men are not essayists.  Perhaps people do not know how easy it is.  Or perhaps beginners are misled.  Rightly taught it may be learnt in a brief ten minutes or so, what art there is in it.  And all the rest is as easy as wandering among woodlands on a bright morning in the spring.

Then sit you down if you would join us, taking paper, pens, and ink; and mark this, your pen is a matter of vital moment.  For every pen writes its own sort of essay, and pencils also after their kind.  The ink perhaps may have its influence too, and the paper; but paramount is the pen.  This, indeed, is the fundamental secret of essay-writing.  Wed any man to his proper pen, and the delights of composition and the birth of an essay are assured.  Only many of us wander through the earth and never meet with her—­futile and lonely men.