It is caused by the cohesive attractive force between like molecules. Adhesion and cohesion are two types of attraction forces that occur between molecules. To Halliday, ‘lexical cohesion comes about through the selection of [lexical] items that are related in some way to those that have gone before’ (p. 310, 330). Sequential Cohesion: When the parts of modules grouped due to the output from the one part is the input to the other, then it is known as sequential cohesion.