Do music theories really become outmoded? If not, what use is to be made of them? This talk will begin by briefly considering the “outmodedness” of scientific theories—sometimes paradoxical—and then contrast that with the situation of music theory. Keeping some salutary cautions in mind, I will recount some past uses of older music theories, good and bad, in order to consider which uses are foundationally legitimate. With this as preface I will then turn to a perspective that permeated theoretical language of the later nineteenth and early twentieth centuries, that known as energetics. In current thinking, energetics is downplayed as vague and ungrounded, but I will argue that concepts we associate with Kurth are indispensable to Schenkerian analysis and even to Riemann’s metric analysis. This will be extensively demonstrated in a close reading of that most energetic work, the first movement of Brahms’s Third Symphony.