I refer to Michael Barr's comments on Neil Ghani's question on cartesian natural transformations. These have been much studied, especially in computer science conrexts, and Michael admits he had seen the replies of Peter Johnstone and myself, in which we independently give precise references to our separate contributions to the study of monads whose multiplication and unit are cartesian natural transformations; such as the monad whose algebras are pointed sets, the multiplication for which is the cartesian natural transformation whose A-component is A+1+1 --> A+1. Accordingly I thought it odd that Michael, in the face of this, trusted his proof that they exist only trivially. Of course, as Peter Johnstone said, Michael's E is usually empty. Ironically, Michael is tha author of a famous and striking paper on the point of the empty set, which inter alia points out earlier errors of this kind on the part of others. Max Kelly.