This article provides an account of the shift in the expression of the internal argument of a small class of dynamic two-place verbs best represented by aider “help” from ‘dative’, i.e., as an indirect object with the preposition à, to ‘accusative’,
i.e., as a direct object with no preposition. This change is not correlated with a change in the meaning of the verbs or with any obvious change in the selectional restrictions imposed on the internal argument. One of the central results of this study is to demonstrate that the shift in argument
realization was systematic and part of a broader change involving the loss of directionality as a property of prepositions in French, explaining its correlation with several other related changes in verbal complementation that also occurred in the 15th century.