I've read a few books about simple living/minimalism but I just finished 'Walden' and wow... it's beautiful. Many patient observations of simple natural phenomenon are wonderful meditations and potent lessons. It seemed just as relevant to present times as to when it was written. I finished feeling like there's so much more to extract from that book, definitely going to read again!

Maybe you were aware, but if not I wanted to share with you fine folks in case you've missed this gem like I had. It is in the public domain in the US (published 1854) so you can get the ebook or audiobook for free from Project Gutenberg!