This article submits that the instances of incipient grammaticalization that are found in the later stages of Latin and that resulted in new grammatical forms in Romance, reflect a major linguistic innovation. While the new grammatical forms are created out of lexical or mildly grammatical autonomous elements, earlier processes seem to primarily involve particles with a certain semantic value and freezing. This fundamental difference explains why the attempts of early Indo-Europeanists such as Franz Bopp at tracing the lexical origins of Indo-European inflected forms were unsuccessful and strongly criticized by the Neo-Grammarians.