This motivation may well relate in some way to the context in which the poet lived and wrote - the effect of time , place and situation. Think about the way the poet might have reacted to the ideas and general beliefs that prevailed in the society in which the poet lived. Especially notice how these ideas and images are sequenced and are built up - this forms the structure of the poem. This is a useful way of considering the effects that are possible using words. However, they are a helpful way of looking at the effect words can be used to create meaning.
Form can be very helpful because it can be made to add to the meaning words already have.
The content of a word, phrase or sentence is the meaning it contains. Poets choose particular words and structures of words to compress the meaning they wish to create. Remember that some words have more than one layer of meaning. Connotation is the lifeblood of poetry. Another use of connotation is irony - when the poet says one thing, but the reader detects a gap between what is said and what is meant.