All civilization has from time to time become a thin crust over a volcano of revolution.

Havelock Ellis (1859-1939) British sexologist, physician, social reformer [Henry Havelock Ellis]

“The Individual and the Race,” Little Essays of Love and Virtue (1922)
    (Source)

In a passage describing the cost of population growth under the Biblical commandment of "Be ye fruitful and multiply." The above is only a fraction of the sentence, which reads in full:

It has meant that all civilisation has from time to time become a thin crust over a volcano of revolution, and the human race has gone on lightly dancing there, striving to forget that ancient warning from a soul of things even deeper than the voice of Jehovah: "At the hand of man will I require the life of man."