Much has been made about Taylor Swift's social media interactions and her revolving cast of high-profile cameos on the 1989 World Tour, but last night, the "Blank Space" singer stripped things down and brought an entire Arizona stadium to tears with a heartbreaking and powerful reminder of her songwriting ability.

Years ago, Swift wrote a song called "Ronan," a tribute to a woman named Maya Thompson, who maintained a blog called Rockstar Ronan that documented her late son Ronan's fight with cancer.

"The thing about childhood cancer is that it's really, really hard to talk about, and it's really not something that you bring up because it makes everyone really, really upset," Taylor explained to the crowd before her acoustic performance of the song, connecting it back to her own mother's diagnosis. "In [Rockstar Ronan] was this account of what it's like to watch cancer take over your life. Since then, I've had cancer hit really close to me and my family."

She went on to talk about the making of the song: "A few years ago, when I was reading the blog, I decided that her account of things was so heart-wrenching and so honest that I took a lot of the things that she said, I put them into a song and I put her as the co-writer — 'cause she is the rightful co-writer of the song called 'Ronan' — and I put it out. All of the proceeds from that song went to the Ronan Thompson Foundation for childhood cancer research."

But before starting into the acoustic rendition, she braced the crowd.

"I can't promise that I will sing it well or not get really emotional," she explained to the crowd, "but I'm going to try. The only time I ever played this was on a show called Stand Up To Cancer. I think that because Maya's here, she deserves it, because she co-wrote it."

Maya was evidently overcome by the gesture, posting about the performance — as well as a shot meeting with Taylor backstage — on her Instagram.

"I still can't believe tonight. I still can't believe you did this. This will forever be one of the most special moments of my life. Thank you @taylorswift for your beautiful heart and for never forgetting my Ro. I love you to the moon and back," she wrote.

Read the full transcript of Taylor's speech below before watching her second-ever live performance of "Ronan" above, but be warned in advance: You will choke up.

"There's a woman here named Maya Thompson. She has lived in this area and brought her kids up in this area. I wouldn't know half as much as I know about childhood cancer and childhood cancer research if she hadn't shared her story about her son, Ronan. The thing about childhood cancer is that it's really, really hard to talk about, and it's really not something that you bring up because it makes everyone really, really upset. The fact that she brought it up — she had this blog called Rockstar Ronan, that I would read every night. In it was this account of what it's like to watch cancer take over your life. Since then, I've had cancer hit really close to me and my family. So because Maya's right there, I would like for you to give her a round of applause, please. A few years ago, when I was reading the blog, I decided that her account of things was so heartwrenching and so honest that I took a lot of the things that she said and I put them into a song and I put her as the co-writer, 'cause she is the rightful co-writer of the song called 'Ronan,' and I put it out. All of the proceeds from that song went to the Ronan Thompson Foundation and childhood cancer research. There are a lot of really, really incredible kids in the city getting some of the best medical treatment. I just wanted to take a moment and try to play this song. I can't promise that I will sing it well or not get really emotional. I'm going to try. The only time I ever played this was on a show called Stand Up To Cancer. I think that because Maya's here, she deserves it, because she co-wrote it."

Taylor Swift Through The Years

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