When the machinery of [Roman] imperial administration broke down in the provinces under the invasion of the barbarians in the fifth century the machinery of the Church remained unbroken.... Ancient families became extinct and the Church became the heir of their lands and slaves and serfs. Small proprietors sought security by committing their lands to the Church and becoming its tenants.

p. 144 - Christianity and the Social Crisis (1907) - Ch.4 Why Has Christianity Never Undertaken the Work of Social Reconstruction?