Levelt (1989: 138) defines linearization as follows: We "arrange information for expression according to the natural ordering of its content". The source of the linearization process is the organization of the speaker's prelinguistic experience. The ordering depends on the topic of discourse and the reader's interest. A natural or iconic ordering can be compared to a path in the sequence from source to goal. Textual coherence depends on iconicity or indexicality in discourse.