In an age triumphant in mechanism, thought tends to run on mechanical lines—on railway lines, in fact. Sometimes we refer, with a pitying smile, to the Victorian idea of progress, which had as its favourite text ‘Go from strength to strength,’ and which was admirably epitomised by Tennyson, the characteristic Victorian poet, in such phrases as :

‘Forward, forward let us range,
Let the great world spin for ever
‘Adown the ringing groves of change’;

or:

‘Men may rise on stepping-stones
Of their dead selves to higher things’;

or a world

‘Where freedom slowly broadens down
From precedent to precedent.’

All very tidy, orderly, and regular. And all very ridiculous ....

We tend to smile at all this now. We now describe ‘progress’ as rhythmic; and a rhythm has its ups and downs, its systole and diastole, its oscillations. Nevertheless, the theory of evolution still binds us with its spell, though some of the Germans are beginning to question it. ‘We are all evolutionists nowadays,’ in ‘progressive’ circles, that is; and we do not usually import German thought until it has become a bit stale in the country of its origin ....