A conceptual world was tentatively described as being the constructed reality reflected by a language as a whole. However, different individuals or different communities of individuals usually have different linguistic repertoires, and it is just as proper to speak of conceptual worlds which are reflected by particular linguistic repertoires rather than by languages. The advent of language alters the picture in a fundamental way. Language use regularly requires the constructing of ad hoc signs. Sentence-level ad hoc signs regularly require the construction of conceptual events. Each new conceptual event slightly alters the corpus of examples which are available to illustrate how one talks about that particular subject matter. The development of the conceptual world of a human child is influenced by the conceptual world of its language almost from its day of birth. From very early in life it learns to interpret its experiences in terms of the elements of the conceptual world of the language.