The significance of the complicated numbering of the propositions in the Tractatus has occasioned much speculation. Wittgenstein's own explanation has, following Stenius, been generally regarded as misleading. But an examination of the Prototractatus reveals that the numbering system was for Wittgenstein principally an aid in the composition of his work. It allowed him to mark out certain propositions which required further work or supplementation, without disturbing the basic structure of the treatise. But the reworking of the Prototractatus to form the (...) Tractatus considerably changed the original order in which the ideas were connected, and thus made it more difficult to understand the Tractatus. Several specific examples make it clear that it is essential to look back at the context of the Prototractatus in order to achieve a correct interpretation of many of the propositions in the Tractatus. (shrink)