Williams was a very cultured man, and by that I mean that he had been places and seen things. He seemed to have a greater outlook on life than most people today do. Since he worked in a medical clinic, he took the images in his of head of those patients and created poems, novels, and short stories. I believe Williams was comparing the frailness and delicate characteristics of the woman in his poem to one of the women that he had seen in the medical ward. Seeing women in a vulnerable state allows the individual to see who a woman truly is.
By writing his poems based on events and things that happened throughout his life, Williams is bringing a personal aspect to his poems, as well as encouraging the reader to feel the similar to the way Williams did when he was writing the poems.
I found another blogger who wrote about Williams, as well. You can find that blog here.