Later scholars added to and refined Wellhausen's theory. For example, the "Newer Documentary Thesis" inferred more sources, with increasing information about their extent and inter-relationship. The "fragmentary theory" was a later understanding of Wellhausen produced by form criticism. This theory argues that fragments of documents — rather than continuous, coherent documents — are the sources for the Pentateuch. Alexander Geddes and Johann Vater proposed that some of these fragments were quite ancient, perhaps from the time of Moses, and were brought together only at a later time. This accounts for diversity but not structural and chronological consistency.