Mrs. Ramsay and Lily Briscoe work as foils because they occupy opposite sides of a question Virginia Woolf is interested in: what is the appropriate sphere for womanly creativity? While the two women seem initially to be entirely different from one another, Lily Briscoe actually finds a lot of inspiration in Mrs. Ramsay. Mrs. Ramsay becomes a kind of spiritual mother for Lily Briscoe, in a way that contrasts interestingly with Mr. Ramsay's relationship to James.
The obvious difference between Lily and Mrs. Ramsay is their feelings about marriage. For Lily Briscoe, marriage represents "a dilution" (a reduction), something from which she wants to protect herself using her painting. For Mrs. Ramsay, it's an inevitability that she, "still always laughing, insist that [Lily] must, Minta must, they all must marry [...] (but Mrs Ramsay cared not a fig for her painting)" (1.9.8).
Mrs. Ramsay, with her investment in Mr. Ramsay's intellect and her faith in the importance of maintaining social norms, really cannot take Lily's painting seriously. Lily's painting is a subtle challenge to the institution of the family that Mrs. Ramsay prizes.
However, like William Bankes (and check out our "Character Analysis" of Lily Briscoe for more on the relationship between those two), Mrs. Ramsay has the sensitivity of mind to appreciate that Lily's painting does mean something. Maybe she doesn't admire Lily's work as Mr. Bankes does, maybe she feels that Lily should give up the painting and be married, but she nonetheless bows her head to be painted by Lily when Lily asks it of her (1.3.7). She knows that Lily's painting has significance to Lily and, as such, should be respected, which is more than either Mr. Ramsay or Charles Tansley give Lily.
See, even though they occupy opposite sides of the marriage question, Lily and Mrs. Ramsay love each other. Mrs. Ramsay is a kind of surrogate mother for Lily Briscoe (who is motherless, and looked after her father); Mrs. Ramsay loves Lily's independence and thinks, secretly, that Lily's looks will wear well into age. Lily, for her part, adores Mrs. Ramsay's investment in the everyday happiness of her family, and admires the love and affection she shares with the rest of the Ramsay family and the world.
In some ways, Lily Briscoe and Mrs. Ramsay become two sides of the same coin. They each focus on the small stuff that makes everyday experience valuable and worth having:
The great revelation perhaps never did come. Instead there were little daily miracles, illuminations, matches struck unexpectedly in the dark; here was one. This, that, and the other; herself and Charles Tansley and the breaking wave; Mrs Ramsay bringing them together; Mrs Ramsay saying, “Life stand still here”; Mrs Ramsay making of the moment something permanent (as in another sphere Lily herself tried to make of the moment something permanent)—this was of the nature of a revelation. In the midst of chaos there was shape; this eternal passing and flowing (she looked at the clouds going and the leaves shaking) was struck into stability. Life stand still here, Mrs Ramsay said. “Mrs Ramsay! Mrs Ramsay!” she repeated. She owed it all to her. (3.3.6)
Mrs. Ramsay works her art with the materials of social life: she draws together men and women into dinner parties and outings to the Isle of Skye. In doing so, she's making her own version of Lily's paintings. Mrs. Ramsay sets scenes that will fix themselves in everyone's memories in the same way that Lily's work catches the essences of moments in time. And perhaps their differences in choice of medium – Mrs. Ramsay's social relations and Lily's paints – has more to do with generation than with any real difference between the two of them. Maybe if Mrs. Ramsay had been born in another time, she would have seized a paintbrush or a pencil rather than a husband in her pursuit of making "life stand still here."
Mrs. Ramsay and Lily do show up one another's differences. But they also set up a kind matriarchal lineage, something to compare with Mr. Ramsay's passing on of power to his son.
Mr. Ramsay (and James) are all about domination (to mask personal insecurity?) and intellectual ambition. Mrs. Ramsay and Lily center their lives around revelations of everyday happiness and small truths. This desire to get at the essence of normal life is a project that Lily learns from Mrs. Ramsay ("[Lily] owed it all to her"), and it's also a project that Virginia Woolf herself pursues (check out our Orlando guide for more).
Many of Mrs. Ramsay’s most important characteristics are highlighted when compared to her husband’s personality. For example, Mrs. Ramsay values harmony and preservation of hope whereas Mr. Ramsay frequently causes discord, getting into petty arguments at the dinner table, and shattering James’s hope of going to the Lighthouse. For Mr. Ramsay, harsh reality is more important than hope. The Ramsay children themselves even can’t resist comparing their parents – they love Mrs. Ramsay unconditionally, whereas they often feel angry at or conflicted about their feelings for their father, occasionally, even to the point of a brutal murder. You can also see a huge difference between Mr. and Mrs. Ramsay when investigating the actual and potential trips to the Lighthouse. At the beginning of the novel, James is excited to go to the Lighthouse with his mother, who seems to make everything fun and hopeful. When James finally goes to the Lighthouse with his father, it is essentially because his father forces him to, taking much of the joy out of the experience.