Coherence: Sense or nonsense

A coherent text "makes sense". Its parts work together and produce an effect on the reader. An incoherent text "does not work". (Except in the extreme case of nonsense poetry.)

To be coherent a text must be cohesive, but this is not enough alone. The following imaginary example is cohesive but not coherent:

"The cat sat on the mat but mats are made of straw. Cat has three letters and this is from Mary. His letter is green, however, mat has three letters."

Coherence implies relevance and meaning too.