This is the second volume devoted to the history of the question of categories, an issue which was also the focus of the collective volume published in 2017. The aim is still to describe some trajectories and perspectives of this history, without claiming an exhaustive overview of it, but rather representing a contribution to a wider project, which is gradually reaching its goal. In this volume the problem of categories has been investigated in the work of further philosophers, from Plato to Quine; in this way the present work complements that done in the first volume. The question of categories has been dealt with in different times and contexts, sometimes coming into the foreground and sometimes concealing itself -- and this is something worthy of investigation in itself. It is also interesting to understand why in particular contexts greater attention is paid to a particular issue that had previously lost its centrality.