From a business-changing perspective of societies and economic activity, the contract is the civilising agent par excellence, replacing violent appropriation of assets with an agreement of wills, which is the primary expression of the social function of the contract. From the French Revolution, this becomes an important progressive instrument based on the principles of freedom and equality. Ownership acquires a social function in addition to the representation of individual wealth and power and becomes an expression of production that can contribute to the common well-being. At the same time, the social function of the contract lies in the creation and fulfilment of legal relations and transactions, bringing together producers and persons, while expressing itself as an expression of human individuality. The binding force of the contract is now qualified from the First World War onwards, in view of the fact that it is too onerous for one of the parties to the contract or significantly alters the economic equilibrium or the basis of the business. The possibility of revising the contract is necessary in Western law, first in Europe – directly exposed to the effects of the First War – and in Brazil, where the resistance of traditional doctrine is broken by case-law. The 1988 Constitution – which has among the objectives of social solidarity and establishes an economic order that envisages the alignment of the laissez-initiative with metaindividual interests – is the source of the principle of sociality incorporated in the Civil Code of 2002, giving a new dimension to the principle of the social function of the contract.