Examines the intellectual origins and legal development of the principle of proportionality in Aristotle, Aquinas and Grotius. Proportionality first applied to the law of self defence, then to police and administrative law, and then to constitutional law. Because interest balancing and proportionality are two different methods referring to two different types of rights the use of the term "balancing" in proportionality discourse should be avoided entirely. Distributive proportionality, economic cost benefit analysis, and lex talionis are three distinct interpretive methods which should not be confused.