In Campbell v. Acuff-Rose Music, Inc., 510 U.S. 569, 114 S. Ct. 1164 (1994), the Supreme Court held that parody, although not specifically listed in 17 U.S.C. 107, is a form of comment and criticism that may constitute a fair use of the copyrighted work being parodied. Id. at 579, 114 S. Ct. at 1171. Parody, which is directed toward a particular literary or artistic work, is distinguishable from satire, which more broadly addresses the institutions and mores of a slice of society. Id. at 580-81, 581 n.15, 114 S. Ct. at 1172, 1172 n.15. Thus, "parody needs to mimic an original to make its point, and so has some claim to use the creation of its victim's . . . imagination, whereas satire can stand on its own two feet and so requires justification for the very act of borrowing." Id. at 580-81, 114 S. Ct. at 1172. The fact that parody by definition must borrow elements from an existing work, however, does not mean that every parody is shielded from a claim of copyright infringement as a fair use. "The Copyright Act has no hint of an evidentiary preference for parodists over their victims, and no workable presumption for parody could take account of the fact that parody often shades into satire when society is lampooned through its creative artifacts, or that a work may contain both parodic and nonparodic elements." Id. at 581, 114 S. Ct. at 1172. Therefore, Houghton Mifflin's fair-use defense of parody, like any other claim of fair use, must be evaluated in light of the factors set out in 107 and the constitutional purposes of copyright law. Id., 114 S. Ct. at 1172. Before considering a claimed fair-use defense based on parody, however, the Supreme Court has required that we ensure that "a parodic character may reasonably be perceived" in the allegedly infringing work. Id. at 582, 114 S. Ct. at 1173. The Supreme Court's definition of parody in Campbell, however, is somewhat vague. On the one hand, the Court suggests that the aim of parody is "comic effect or ridicule," but it then proceeds to discuss parody more expansively in terms of its "commentary" on the original. Id. at 580, 114 S. Ct. at 1172.