A metaphor is an image based similarity within difference. Metaphors ask the reader to intuitively and meditatively consider the similarity between two words that are apparently different. There is some vagueness in this process, but that is to be desired. However, imagery compensates for the lack of precision by its increase in vividness. They become clear and memorable.
Images also speak directly to the heart.
They are emotionally charged and induce us to action. Images also bring our attention to old truths in new ways. Jesus' parables served this function. Meter Meter is common to Greek, Roman, English, and American poems, but Hebrew meter is different. Meter is defined in relationship to rhythm.