GTD and the Zettelkasten methods are bottom-up processes, which means we don’t start with setting a goal that we want to reach, but instead we work with the things that we have at the current moment. The Zettelkasten – similarly to the Natural Planning Model of GTD – naturally let your notes to form into a concrete thing. It is the complete opposite of the traditional view of research which starts by setting the final goal or state that we have to reach.