Why does frank collymore started to describe the scene where he saw the woman in the poem end day?

Lapiz Dominoes

He describes the setting simply as context to describe in wonderfully sensitive detail the expressions, movement and beautiful pathos of the aged woman, ego - less now to meet and welcome her perceived maker. To elaborate the context after the main point of the poem would probably, in the narrator`s mind, detract from the significance of her state.. That is the narrator`s device.