Last Friday, Sia released her highly anticipated sixth album "This is Acting". One of the most captivating elements of this album is that Sia wrote each track with the intention of another artist singing it. That’s right, all twelve tracks were rejects from queens of pop like Beyoncé, Rihanna, and Adele. Thence the collection's title "This is Acting."

This project isn’t the first time Sia’s written songs for other artists. We have her to thank for Beyoncé’s “Pretty Hurts,” Rihanna’s “Diamonds,” Britney’s “Perfume,” and a host of other Top 40 hits. This album, however, is our first chance to hear some of Sia’s songs that didn’t make pop music’s original cut.

Sia wrote “Alive," the lead single of the album, with and for Adele. Adele recorded a demo of the song but ultimately chose “When We Were Young,” another collaboration with Sia, for her "25" album. This is Acting's second single, “Bird Set Free,” was originally written for "Pitch Perfect 2". Similar to “Alive,” the song was rejected in favor of a different Sia creation titled “Flashlight.” “Bird Set Free” was then pitched to Rihanna and later Adele.

You can also hear Rihanna's influence on “Cheap Thrills” and “Reaper," both written with the artist's eighth album "Anti" in mind.

“Footprints” came into the world as a ballad intended for Beyoncé. “Cheap Thrills” was sent to Icona Pop after Rihanna’s dismissal. The uplifting tune "Unstoppable" went through rounds with both Katy Perry and Demi Lovato. Shakira was originally intended to sing “Move Your Body.” (And though no one's saying so, I speculate “Sweet Design” was written with either Shakira or Beyoncé in mind.)

It's hard not to wonder what these artists would have changed about Sia's songs had they actually released their own versions of them. In an article published by Vulture.com, Lindsay Zoladz speculates:

In some alternative universe, could Adele’s “Alive” have been her comeback single, rather than “Hello”? Would it have been as big a hit? What sort of reworking would Beyoncé do to “Footprints” to make it her own? Would Icona Pop have had a second smash if they’d recorded the punchy “Cheap Thrills” instead of their tepid 2015 single “Emergency”? Does Rihanna’s rejection of “Reaper” tell us anything about the sound of "Anti"?

Needless to say, this album will get you thinking. Listening to these tracks is like solving a series of puzzles. Who was this track intended for? How many people rejected it? Would I like it just as much in someone else's voice?

While some critics find this approach at an album less thoughtful than Sia’s previous work, namely her preceding album, "1000 Forms of Fear", I love the concept of "This is Acting". Sure, the intense emotions behind each track of "1000 Forms" are generally absent from this new set of tracks. Even so, there’s no denying that Sia can write an amazing pop song. I think repurposing the art she intended for other voices in this way was an awesome and empowering decision. Despite being rejected by several influential artists, Sia recognized the beauty in her work and wasn't afraid to share it. Though I love many of the artists she worked for, I’m overjoyed to hear Sia’s voice on each of these tracks.