We just wrapped up a couple of fun, family-filled days in the Windy City. It was our Last Blast of Summer — a little mini get-away before the kids begin the 2014/15 school year. We loaded up the Navigator — with 23 DVDs for our 4-hour trip — and established the ground rules: 1) No whining about sore feet, 2) Don’t be dicky.

It was a whirlwind of perfect weather, fabulous food, window shopping, double ear-piercing, Segway touring, Garrett’s popcorn eating, park visiting, and lakefront walking. The four bravest Willi ventured to the Willis Tower SkyDeck.

The two not-so-brave Willi went to the Adler Planetarium instead… where we felt quite dumb and insignificant. The vast expanse of the universe can do that to you. Even the high-achieving, all-about-me 17-year-old said, “Wow. This is humbling.”

Throughout most of the trip, my four boys rushed ahead, always intent on getting to the next destination. Mary Claire and I lagged behind, people-watching, window-gazing, taking in all the sights and sounds. She slowed every time we passed a homeless person, eager to read their signs and better understand their plight.

“It’s hard, isn’t it?” I asked as we stepped into swanky shops where she modeled with the mannequins. “We understand intellectually that there’s a huge divide between the wealthy and the poor, but it’s made so apparent, I think, in a big city.” Mary Claire nodded.

“It’s so surreal,” she said, “to see homeless people sitting outside store windows where one dress or purse might cost $1,000. It makes me feel helpless.”

“It’s overwhelming, for sure,” I said. “But you’re never, ever helpless. There’s always something you can do to brighten someone else’s day, to change your corner of the world, right? Even if it doesn’t involve money, it’s important to always acknowledge that everyone you see is another human being, just like you — no better, no worse. And even if all you have is a smile, you can give that.”

We kept walking, and I saw her before Mary Claire did. An older woman, dirty, disheveled, head bowed, sat behind a cardboard sign that read, “I’m just hungry.” Mary Claire looked at me with questioning eyes, and I nodded. She took the bag of Giordano’s pizza she was carrying and bent down eye-to-eye with the woman. “Would you like this?” she asked softly.

The woman looked up, smiled, gray teeth visible, face wrinkling, and said, “Thank you, child. Thank you.”

Mary Claire was moved by the interaction, overcome with emotion. “It’s not enough,” she said as we walked on. “It is,” I said. “You made a difference. Remember the starfish story? You made a difference to one.”

We arrived home last night, road-weary, stuffed with popcorn and pizza, and ready to sleep in our own beds. The kids unloaded the car, took their belongings to their respective rooms. Gus emerged shortly thereafter from the basement, holding what appeared to be a dead baby mouse by its tail. “I found this outside my room.”

Mary Claire took it from him, gently held it in her hand. And she noticed that it was still breathing. It moved, and she squealed. “Mom! Mom! It’s alive! What should we do? Should we take it to the vet?”

“Not the vet!” George yelled, always the pragmatist. “That will cost a million dollars that we don’t have!”

“Let’s do a little research online,” I said, Googling “How to take care of a baby mouse.” We made a nest for her in a small box, lined it with paper towels, and put her under George’s borrowed desk lamp. We found out that we needed kitten formula, a paintbrush, and some Q-Tips to feed and nurture her.

“Will you take me to the store?” Mary Claire asked. “I’ll buy the stuff with my own money. I’ll take care of her, Mom.”

“You’ll have to feed her every 1-2 hours, including during the night,” I warned.

“I will. I will. I promise I’ll take care of her. I’ll set my alarm. Please, Mom?”

And so we got back into the car, Mary Claire, George, and I, and headed out to find kitten formula.

The mouse’s breathing was labored during our trip, her movements jerky and erratic.

“She’s a sick baby, Mary Claire,” I said. “You know she might not make it, right?”

“I know, Mom,” she said. “But I have to try.”

“Why don’t you hold her in your hand?” I suggested. “She’s so cold.”

Mary Claire talked to the baby mouse softly, cradled her, rubbed her back. “We’re getting you some food,” she said. “Hold on.”

We pulled into the parking lot, and Mary Claire yelled, “Don’t go now! Don’t leave us yet!” She was crying into her hands where the baby lay silent and unmoving. I rubbed the baby’s back, trying to elicit a response, but there was none. Her chest no longer rose and fell with breath.

She was gone.

“I didn’t even get to name her,” my girl cried.

When I was a little younger than Mary Claire, I found an unbroken, abandoned robin’s egg on the ground outside of our apartment. I ran into the kitchen with that egg cradled carefully in my hands and convinced my Mom that I was going to be that baby bird’s mother. I was going to make sure it hatched, then I would feed it and take care of it and we would be BFFs forever.

My Mom could have said, “Silly girl, that baby bird is already dead,” but she didn’t.

Of course she didn’t.

She helped me find a box that we layered with towels and shredded bits of paper. She helped me position that egg just right under a warming lamp. And every hour, I’d check my egg, watching for a shiver, a crack, a sign of life. My Mom would say, “Anything happening, Trinks?” And I would say, “Not yet.”

After a couple of days, we began to have the harder conversations. Mom would say to me, “You’ve been a good Mama to that baby bird, Sweetie. No matter what happens, you’ve taken good care of her.” And I would nod, holding back tears, because I knew what the “no matter what happens” part of the conversation meant.

I dug through my sticker collection — many of which I’d bought when I received the coveted Go-To-the-Teacher-Store-with-Miss-Dowling award — and found one that said, “CHAMPION!” I gently placed the sticker on the shell and said to my Mom, “I’m going to name this baby Champ because if she makes it, she really will be a champion.” My sweet Mom nodded and rubbed my shoulders.

She knew. Of course she knew.

When it was finally time to let that baby go, I carried the box out to the field behind our apartment and buried it. I cried, my Mom cried. We said a prayer and wished that baby well. I will never — never — forget how grateful I was to my Mom for giving me that experience.

So last night, after our sweet baby mouse had breathed its last breath, we wrapped her gently in soft paper towels and buried her under Mary Claire’s favorite tree. “I really wanted to take care of her,” Mary Claire cried. “She never even had a chance.”

“I know, Sweets,” I said. “But you know what you gave that baby? You gave her a warm, soft, safe spot to let go. If you hadn’t taken care of her, she would have died alone in the basement. But instead, she got to have your warm hand as she left this world. What a gift you gave her.” And we hugged and cried together as my girl let go of her baby mouse Mama dreams.

No matter how vast this universe may be, no matter how much the Adler Planetarium may remind us of our tiny spot in this expanse of time and space, we are all here together, in our own corner of this little blue planet, and the only thing that matters is that we take care of each other. Always. Without fail, without judgment, in whatever ways we are able.

If we are not here to love and tend each other, we are not really here at all.

Thank you, Sweet Mary Claire, for the reminder.