In this paper I present an abstract theory of senses, thoughts, and truth, inspired by ideas of Frege. "Inspired" because for the most part I shall not pretend to interpret Frege in a literal sense, but, rather, develop some of his ideas in ways that seem to me to preserve important aspects of them. Senses are characterized as identifying properties; i.e., roughly, as properties that apply, in virtue of their logical structure, to exactly one thing, if they apply to anything at all. When Frege's analysis of sentences in terms of function and arguments is combined with his analysis of quantification as higher-order predication, all sentences (formal and informal) can be analyzed in various ways as a function (predicate) applied to one or more arguments. This allows for an abstract characterization of thoughts as senses that combine other senses in a uniform way, and whose truth derives from their instantiation by corresponding items of reality.