This chapter identifies elements that are common to sacrificial practices and events: signification of transcendence that requires discipline or denial of natural desires to point to what is beyond nature; suspense of offering without assurance of its intended outcome, illustrated in Pascal’s wager and Kierkegaard’s leap of faith; conditionality of the gift as a result of its qualifications, ritual performance, and contingent reciprocity of the sacred recipient; self-sacrifice through partial identification with what is offered (what Marcel Mauss called the “intermingling” of persons and things in sacrifice). This chapter offers a tentative definition of sacrifice as a costly act of self-giving, in denial of natural inclinations, that is offered in suspense, under conditions that threaten failure, for the purpose of establishing a relation with transcendent reality. This definition is developed in light of Kathryn McClymond’s proposal of “polythetic classification” of sacrifice.