Imagery is a literary device in which descriptive language is used to inspire mental images in the mind of the reader. Writers who employ imagery in their work carefully choose words and language that appeal to the five senses. In addition to evoking mental images, imagery can also be used to convey emotion.
In his poem "The Road Not Taken," Robert Frost uses a great deal of visual imagery (as well as some auditory imagery) to help the reader create a picture in his/her mind and to communicate the emotions of the narrator, who is indecisive, regretful, and ultimately content.
The traveler in the poem is walking in the woods and comes to a fork in the road. The speaker stands at the fork for a time, looking at each of the two paths and contemplating which one to walk down.
Frost describes the "yellow wood" and the two paths the traveler must choose between. Both paths are very similar and equally worn, but the traveler can only choose one. By describing the visual similarities shared by the two paths, Frost communicates the traveler's difficulty in making a choice: one path is no more or less appealing than the other, which leaves the narrator with nothing to base their decision on.
Frost's use of visual imagery allows the reader to imagine themselves in the traveler's position, standing in the woods at the place where two roads split, trying to decide between them, and regretting the inability to travel both.
In the final stanza of the poem, Frost uses auditory imagery to illustrate the narrator's simultaneous disappointment and satisfaction: "I shall be telling this with a sigh." The reader can almost hear the traveler's sigh while reading Frost's words. This example of sound imagery is used to once again illustrate the traveler's imagined wistfulness in not being able to travel both paths.