The historically informed performance (HIP) movement, which by the 1970s had transformed the interpretation of Baroque and Classical repertoire, rested on a deceptively simple premise: that a musical work is best served when realized with the instruments, tunings, tempos, and playing techniques available to its composer. Advocates argued that the modern concert tradition had accreted a patina of anachronism - vibrato-laden strings, swollen orchestras, steel-strung pianos - that obscured the sonic intentions encoded in eighteenth-century scores. Strip away these encrustations, the reasoning went, and one recovers not merely an older sound but the work itself, heard as its author meant it to be heard. The philosophical difficulty in this program lies in its governing word, authenticity. Richard Taruskin, the movement's most formidable internal critic, contended that the term smuggles in a claim it cannot redeem. To reconstruct the acoustic conditions of a 1725 performance is not to reconstruct the aesthetic experience of a 1725 listener, for whom that sound was ordinary rather than archaic, expected rather than recovered. The modern audience that thrills to gut strings and valveless horns hears them against a backdrop of twentieth-century listening habits; the very strangeness that certifies the performance as authentic is a strangeness unavailable to the original ear. Authenticity, so construed, is less a property of the past than a projection of present desire onto it. Yet Taruskin's critique, for all its force, does not dissolve the practice it interrogates. What the HIP movement produced, on his own generous account, was not a fraudulent archaeology but a genuinely modern performing style - one whose leanness, transparency, and rhythmic vitality answered to distinctly contemporary tastes, tastes shaped in part by modernist aesthetics far removed from the Baroque. The historical apparatus, in this reading, functioned less as a constraint than as a license: the appeal to the composer's era freed performers from the interpretive orthodoxies of the mainstream tradition and legitimated experiment under the banner of fidelity. Recovery was the rhetoric; renewal was the achievement. This reframing carries a cost that its proponents rarely acknowledge. If the value of historically informed performance is finally its modernity, then the scholarship on which it prides itself - the treatises consulted, the iconography examined, the surviving instruments measured - becomes ornamental, a source of inspiration rather than of authority. Few practitioners would accept so deflationary an account of their labor. The historical evidence does constrain: a performer who ignores the documented conventions of ornamentation is not making a modern choice but an incompetent one, and the difference is not merely rhetorical. The evidence underdetermines interpretation without rendering it arbitrary. The lasting contribution of the debate, then, may be neither the sound the movement recovered nor the illusion it is accused of peddling, but a sharpened awareness that every performance is an act of interpretation situated in its own moment. To perform is unavoidably to choose, and no quantity of historical data discharges the performer from responsibility for the choice. The past does not play itself; someone in the present must, and that someone is never invisible.