"The Ancient Mariner is a story told in picture"; elucidate.
The quote undoubtedly refers to the fact that the poem is vividly descriptive. The imagery is abundant and the use of color is throughout the poem. One example is in Part II, lines 111-114 with the description of a "hot and copper sky" and a "bloody sun", another example is in Part III, lines 190-194 with the description of Life-In-Death and her red lips, yellow locks, and white skin. The action is vividly described in the poem as well. In Part VI, lines 488-495, the Mariner describes how a spirit stood by each of his dead companion's bodies and then waved as it left each body Even the sound imagery is vivid. One example of that is in Part VII, lines 546-549 with the description of the deep sound that comes from under the water to sink the Mariner's ship. The poem is one long description of scene, sound, and action.
The poem is written with vivid description and lots of rhyme, rhythm, and imagery to create the movie behind your eyelids as it is read. It's sing-songy quality also helps to bring it to life. There is no way anyone can read this story of how the wedding guest is "held" in a trance while albatross' are shot, sea snakes glitter, ghost ships appear and gamble for the lives of men, and the ship magically brings the mariner back to his home port shortly before sinking without seeing every detail as if it unfolded right before your eyes. The pictures appear easily as the words are read. It's an amazing journey!