Meg and Calvin talk as they walk to the Murrys house, and it's clear that this is the beginning of a close friendship. When they arrive at the Murrys, Mrs. Murry warmly welcomes Calvin as she cooks a stew over a Bunsen burner in her lab, which is attached to the kitchen. Calvin can't believe how lucky Meg is have to a mother like her—his own mother is nowhere near as loving and beautiful. He calls home to tell his mother that he won't be home for dinner, but comments to Meg that he doesn't think his mother would have noticed he was missing dinner even if he hadn't called.
Calvin's incredulous reaction upon meeting Mrs. Murry is the first wake-up call to Meg that she is incredibly lucky to have a mother who loves her as Mrs. Murry does. That she is cooking dinner over a Bunsen burner highlights Ms. Murry's own endearing peculiarities. Seeing her mother through Calvin's eyes Meg can appreciate her mother's love for her in a new way.
As they wait for dinner to be ready, Meg explains to Calvin a little bit about her father, and then astounds Calvin by helping him out with his math homework (he's several grades above her). Mrs. Murry explains that Mr. Murry used to play math games with Meg, hence her advanced understanding. Calvin feels absolutely at home with the Murrys, because he's found people who are different the way he is (he too is unusually smart). When he says something about not feeling alone anymore, Meg is surprised, because to her he seemed one of the most popular and well-liked kids at her school. "For all the most unimportant reasons," Calvin replies.
After dinner, Calvin goes upstairs to read Charles a book before goes to bed (Charles requests the Book of Genesis), and Meg tentatively asks her mother if she's upset. Mrs. Murry says yes, because she misses their father so much, and Mrs. Whatsit's mention of the tesseract has aggravated it. When Meg presses for a further explanation, her mother tells her that with human limitations, there are just some things that can't be understood. They talk about how Charles can understand more than most people and is very different. When Meg protests that he doesn't look any different, Mrs. Murry gently reminds her that people are more than their appearance: "Charles Wallace's difference isn't physical. It's in essence."
Meg, the math whiz, as always wants a clear and final answer, but must learn to curb her impatience and realize that there are limits to what she can understand. The fact that her brilliant scientist mother tells her this as something that she must accept shows how true this must be—science can't explain everything; there aren't always clear answers. Mrs. Murry also needs to remind Meg how unimportant physical appearances are in judging people, as in the case of Charles Wallace.
Calvin comes downstairs and takes Meg for a walk outside. He asks her more about her father, and she tells him that he's a brilliant physicist who was working for the government on a top secret project when suddenly, a year ago, they stopped hearing from him, and the government told them he was on a secret and dangerous mission, and that they would let the Murrys know as soon as they heard anything. Calvin alludes to the rumors about her father abandoning their family, but when Meg gets defensive he assures her he never believed the rumors. As tactful as Calvin is trying to be, Meg begins to cry. When she takes her glasses off to wipe her eyes, Calvin quietly tells her to go on wearing her glasses in front of everybody else, because he doesn't want anyone else to know what beautiful eyes she has.
Friendships like the one between Meg and Calvin (which may blossom into a romance) make the world go ‘round: where would these two misfit kids be if they didn't love one another. Receiving love and affirmation from another is so important to happiness in this novel. More importantly, there is an implication here—expressed more fully later in the novel—that love is only possible when people are different, that love is a kind of bridge that forms between and because of difference.
At that moment, Charles Wallace steps out of the shadows and apologizes for interrupting, but tells them that the time has come for them to find Mr. Murry. Mrs. Whatsit and Mrs. Who suddenly appear out of nowhere, and the children then meet their third companion, Mrs. Which, whose voice and appearance are strangely distorted (for her to fully materialize would be too tiring).
The children can't even fully see Mrs. Which, another barrier to understanding her, but she is the wisest of all the Mrs. W's. As with Charles, it is not her appearance but her essence that matters.