rise, expand, bubble, swell, and spout like a volcano. To all races
there has been something devilish, or at least demonic, in the action of
leaven. It is true that in the ancient parable the comparison lay
between leaven and the kingdom of heaven. The kingdom of heaven was like
a little leaven that leavens the whole lump, and Goethe says that
Mephisto, one of the Princes of Evil, also works like that. But whether
we call the leaven a good or evil thing makes little difference. The
effect of its mysterious powers of movement and upheaval is in the end
salutary. It works upon the lump just as the catfish, that demon of the
deep, preserves the lumpish cod from the apathy and degeneration of
comfort, and as Mephisto, that demon of the world, acts upon the
lethargy of mankind working within him, stimulating, driving to
production as a devil may.

"A society needs to have a ferment in it," said Professor Sumner of
Yale, in his published essays. Sometimes, he said, the ferment takes the
form of an enthusiastic delusion or an adventurous folly; sometimes
merely of economic opportunity and hope of luxury; in other ages
frequently of war. And, indeed, it was of war that he was writing,
though himself a pacific man, and in all respects a thinker of
obstinate caution. A society needs to have a ferment in it--a leaven, a
catfish, a Mephisto, the queer, unpleasant, disturbing touch of the
kingdom of heaven. Take any period of calm and rest in the life of the
world or the history of the arts. Take that period which great
historians have agreed to praise as the happiest of human ages--the age
of the Antonines. How benign and unruffled it was! What bland and
leisurely culture could be enjoyed in exquisite villas beside the
Mediterranean, or in flourishing municipalities along the Rhone! Many a
cultivated and comfortable man must have wished that reasonable peace to
last for ever. The civilised world was bathed in the element of calm,