Lois Lane knows that Superman can fly, but she does not know that Clark Kent can fly. How can that be, given that Superman and Clark are one and the same? To answer this question, Frege famously distinguished the reference of a name (the thing it is a name of) from what he called its 'sense' or 'mode of presentation'. The sense was meant to capture our (necessarily limited) perspective on reference and to explain the difference in 'cognitive value' between "Superman can fly" and "Clark can fly". Frege's distinction has been widely discussed in the last century, but much about it remains unclear. In this collection, Richard Kimberly Heck, one of the world's foremost experts on Frege's philosophy, distinguishes three aspects of Frege's famous 'puzzle' and explores the connections between them. Their wide-ranging discussion touches on issues in philosophy of mind, philosophy of language, philosophy of logic, the history of analytic philosophy, and meta-philosophy. Heck argues that, while
