"516 have been the understanding of anyone offered Grokster’s suggestively named Swaptor software, its version of OpenNap. And both companies communicated a clear message by responding affirmatively to requests for help in locating and playing copyrighted materials. In StreamCast’s case, of course, the evidence just described was supplemented by other unequivocal indications of unlawful purpose in the internal communications and advertising designs aimed at Napster users (“When the lights went off at Napster … where did the users go?” (ellipsis in original)). Whether the messages were communicated is not to the point on this record. The function of the message in the theory of inducement is to prove by a defendant’s own statements that his unlawful purpose disqualifies him from claiming protection (and incidentally to point to actual violators likely to be found among those who hear or read the message). Proving that a message was sent out, then, is the preeminent but not exclusive way of showing that active steps were taken with the purpose of bringing about infringing acts, and of showing that infringing acts took place by using the device distributed. Here, the summary judgment record is replete with other evidence that Grokster and StreamCast, unlike the manufacturer and distributor in Sony, acted with a purpose to cause copyright violations by use of software suitable for illegal use. Three features of this evidence of intent are particularly notable. First, each company showed itself to be aiming to satisfy a known source of demand for copyright infringement, the market comprising former Napster users. StreamCast’s inte rnal documents made constant reference to Napster, it initially distributed its Morpheus software through an OpenNap program compatible with Napster, it advertised its OpenNap program to Napster users, and its Morpheus software functions as Napster did except that it could be used to distribute more kinds of files, including"