“The Grimms have often been criticized, especially by critics in the last 50 years, for having changed and edited the tales from the first to the seventh edition. That is, they never lived up to their own words that the task of the collector is to record the tales exactly as they heard them. In other words, various critics have complained that the Grimms’ tales are inauthentic folk tales. But this is a ridiculous if not stupid argument, for nobody can ever record and maintain the authenticity of a tale. It is impossible. And yet, the Grimms, as collectors, cultivators, editors, translators, and mediators, are to be thanked for endeavoring to do the impossible and to work collectively with numerous people and their sources to keep traditional stories and storytelling alive. In this respect their little known first edition deserves to be rediscovered, for it is a testimony to forgotten voices that are actually deep within us. Hence, the irresistibility of the Grimms’ tales that are really not theirs, but ours.” Read more at The Public Domain Review
You can view/download the original book at Wikisource (in German).