What's Puzzling Gottlob Frege?

By any reasonable reckoning, Gottlob Frege's ‘On Sense and Reference’ is one of the more important philosophical papers of all time. Although Frege briefly discusses the sense-reference distinction in an earlier work (‘Function and Concept,’ in 1891), it is through ‘Sense and Reference’ that most philosophers have become familiar with it. And the distinction so thoroughly permeates contemporary philosophy of language and mind that it is almost impossible to imagine these subjects without it. The distinction between the sense and the referent of a name is introduced in the second paragraph of ‘Sense and Reference.’