Mrs. Whatsit is a somewhat eccentric older woman. Mrs. Murry has never met her. At the opening of the novel, while Meg, Charles Wallace, and Mrs. Murry are having a late night snack of sandwiches around the kitchen table, unable to sleep because of a violent storm, they hear the sound of someone at the back door of Mrs. Murry's lab.
Meg thinks it is a tramp, but Mrs. Murry nevertheless fearlessly goes to see who is there.
Mrs. Murry brings Mrs. Whatsit back to the kitchen and offers her a cup of hot chocolate. She then offers her a sandwich. She also helps her take off her boots and urges Mrs. Whatsit to spend the night with them. Overall, Mrs. Murry treats her strange guest with dignity and hospitality.
This shows that Mrs. Murry is a kind and compassionate person. She is willing to take a risk with a stranger rather than shut the door against her in fear. Her welcoming behavior therefore reveals her courage. She also instinctively trusts Mrs. Whatsit, even though Mrs. Whatsit has confessed to having stolen Mrs. Buncombe's sheets. This shows Mrs. Murry is a good judge of character.