The article is an attempt to look at the mediaevalist work of Jacek Banaszkiewicz through the prism of statements of other scholars using the comparative method (including M. Handelsman, M. Małowist, M. Tymowski, K. Modzelewski). The aim is to answer the question of whether there is a set of guidelines that every comparatist should follow. The specific issues discussed here include the role of difference and similarity in comparison, the notions of function, analogy and homology, geographical and chronological limitations of comparative studies, and the role of influence and reception.