Textual coherence: internal coherence or external coherence?

This article shows how the different treatments of phenomenon of the textual coherence have taken two fundamental directions: a) to try to explain the coherence by one internal principle of the text, b) or to try it by one external principle. It will be argued in this paper that only from the text itself (internal coherence) could offer one satisfactory answer to such question. Meanwile, it demonstrates how external factors colaborate to the establishment of the textual coherence