IN THIS debate about corporate advertising on behalf of political campaigns, it seems one major point has been missing. Money is not speech. The Constitution guarantees us freedom of expression, not the limitless means to broadcast this expression. If that were true, then each of us should be able to reach 300 million readers, listeners, or viewers with our every opinion. Corporations are not at all prohibited from saying what they like; they are merely restricted, rightly, from the amount of money they can spend to amplify their speech.