Murray N. Rothbard - The Ethics of Liberty

All other persons and groups in society (except for acknowledged and sporadic criminals such as thieves and bank robbers) obtain their income voluntarily: either by selling goods and services to the consuming public, or by voluntary gift (e.g., membership in a club or association, bequest, or inheritance). Only the State obtains its revenue by coercion, by threatening dire penalties should the income not be forthcoming. That coercion is known as "taxation," although in less regularized epochs it was often known as “tribute." Taxation is theft, purely and simply even though it is theft on a grand and colossal scale which no acknowledged criminals could hope to match. It is a compulsory seizure of the property of the State's inhabitants, or subjects.