It seems as if we've finally begun to figure out how to get into those mysterious houses built just after the turn of the century by Schoenberg and Webern. To say that we've found the keys does not, however, represent an apt way of narrowing the metaphor, since, for better or for worse, they built these houses without doors. At best they may be said to have painted door-like signs on their exteriors, or, in some cases, to have graced their facades with doors grouped in threes and fours, leading not to the inside but instead to one another and back out. The use of keys is not recommended in connection with attempts to penetrate doorless, lockless houses, even if these be the well-worn master keys with which much success has been had in the past. Entry is gained only by dismantling part of the structure, for which task keys are not the implement of choice. New tools are needed to do this kind of work: powerful precision tools which can be modified to meet the demands of particular jobs. The tools developed in recent years by people who care deeply about motivic or, as it is often called, atonal music do appear to be tools of the required sort. With respect to power, precision, and flexibility, the set-theoretic concepts developed by Babbitt, Lewin, Perle, Martino, Howe, and, most notably, by Forte constitute an avenue of approach to this music which is impressive in its potential. At the same time, the nascent overview of what this music is all about, one emerging as a result of initial attempts to apply these concepts, is not an encouraging one and tends to undermine the positions of those who regard this repertoire as a musical legacy of the first rank. The problem as I see it resides not in the tools but in the manner of their application. Precision equipment for penetrating facades it not designed to be hurled like a demolition ball at the objects it is meant to transform. One is better off, on the whole, with crude tools employed with subtlety than with a refined technology for which one lacks the appropriate strategies. In my view, misuse of the new technology for dealing with motivic music has taken the form of attempts to apply all of the relations defined in the theory of unordered pitch-class sets to each an every analytical context. Instead of regarding the theory as a universe of possible relations and trying to determine criteria for deciding which relations are actually germane to