I was just paging through a copy of "The Princeton Companion to Mathematics. Tim Gowers and all who contributed to this volume did a superb job in producing such a comprehensive and in-depth look at the culture and content of mathematics. There is, I think, one lacuna in this otherwise wonderful book. Eugenia Cheng wrote a very fine two page explanation of the concept of a category for this volume. But in the 350 pages devoted to the various branches of mathematics, 350 pages divided into 26 topics such as Algebraic Geometry, Algebraic Topology, Differential Topology, Harmonic Analysis etc, there is no article on Category Theory. This should be contrasted with the 11 page article on Set Theory, and the 12 page article on Logic and Model Theory. What does this say about the general perception of the proper role for category theory in mathematics? Carl Futia