What is the difference between seeing and thinking? In this book, philosopher Ned Block argues that there is a joint in nature between perception and cognition, but also that cognition penetrates perception. The first half of the book is devoted to explaining the principled differences between perception and cognition, while the second half shows how thinking affects seeing, discusses the problem cases of mental representation of causation and numerosity, and draws the consequences for theories of consciousness. Along the way, Block tackles questions such as: Is perception conceptual and propositional? Is perception iconic or more akin to language in being discursive? What is the difference between the format and content of perception, and do perception and cognition have different formats? Is perception probabilistic, and if so, why are we not normally aware of this probabilistic nature of perception? Are the basic features of mind known as core cognition a third category in between perception and cognition? This book explores these questions not by appeals to intuitions, as is common in philosophy, but to empirical evidence, including experiments in neuroscience and psychology. This is an open access publication, available online and distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives 4.0 International licence (CC BY-NC-ND 4.0), a copy of which is available at http: //creativecommons.org/licenses/by-nc-nd/4.0/. Enquiries concerning use outside the scope of the licence terms should be sent to the Rights Department, Oxford University Press.