Popsugar Living Astrology The Best Astrology Books Start Off the New Year Guided by These 9 Astrology Books 11 January 2020 by India Yaffe View On One Page Photo 9 of 9 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 9 The Power of Mercury Sometimes, Mercury goes into retrograde. If you want to learn a little bit more about what exactly that means, grab The Power of Mercury ($25). The Power of Mercury $25 from freepeople.com Buy Now Previous Next Start Slideshow ShoppingAstrologyBooks