If my understanding of Kant is correct, then all analysis (i.e. taking things apart) is synthesis (i.e. putting things together) in reverse, and therefore the latter is a necessary prerequisite of the former. According to him, our minds very first brush with the real world (whatever that might be) is in the form of the "manifold" of raw sensory signals sans any form whatsoever (not even spatial or temporal arrangement), and the only way we can make sense of that manifold of signals or data is to reduce them through a process of combination by commonalities and separation by lack thereof. All objects, categories and concepts ultimately spring from this process of synthesis, some of it involuntary (e.g. the arrangement of certain inputs into three dimensional space) and some of it volitional (e.g. the positing of concepts and categories). Analysis is taking these constructs apart, much like one takes apart a mechanical watch. Except that the exercise tells us more about how our brain puts things together than what the thing actually is.