There is no historical fact that did not owe its origin to social economics; but it is no less true to say that there is no historical fact that was not preceded, not accompanied, and not succeeded by a definite state of consciousness.
The Materialist Conception of History, 1891, Ch. 6.
Children like to work, and are always eager to imitate the work of adults.
Utopian Socialism in the Nineteenth Century, 1913, Ch. 5.