User blog comment:DancePowderer/Metaphysical Horticulture/@comment-89.139.198.106-20120802133008/@comment-4493594-20120802142430

I guess the knowledge of DFs is older than the knowledge of how they actually work. Some people MIGHT have witnessed one thing or the other but it probably took some time till someone actually bothered to collect the knowledge and put all the information together.