Back in 2009, when Evan was seven, his family adopted a cat named Macha from City Kitties, an animal rescue in Philadelphia. The boy immediately took to the feline, and to show City Kitties his appreciation for his new pet, he wrote them a nice handwritten thank you note which included a $46.75 donation that he had saved up from his allowance.

City Kitties posted a photo of the letter on their Facebook page, which encouraged dozens of other cat lovers to match Evan's donation.

The next year Evan sent another letter and donation, this time using money he got from selling figs from his parent's fig tree. By 2011 he was able to donate $97.

2012 saw Evan's first cursive letter, and $110, which his parents have already matched.

Along the way City Kitties surprised Evan by giving him another cat, Calvin. Calvin and Macha get along, although Evan conceded in one of his letters that Macha was a little rough with the newcomer at first.

You can see all of Evan's sweet notes below. And you can donate to City Kitties Rescue through their Facebook page.