And Kant also commits the fallacy of supposing that This ought to be means This is commanded. He conceives the Moral Law to be an Imperative. And this is a very common mistake. This ought to be, it is assumed, must mean This is commanded; nothing, therefore, would be good unless it were commanded; and since commands in this world are liable to be erroneous, what ought to be in its ultimate sense means what is commanded by some real supersensible authority. With regard to this authority it is, then, no longer possible to ask Is it righteous? Its commands cannot fail to be right, because to be right means to be what it commands. Here, therefore, law, in the moral sense, is supposed to be analogous to law, in the legal sense, rather than, as in the last instance, to law in the natural sense. It is supposed that moral obligation is analogous to legal obligation, with this difference only that whereas the source of legal obligation is earthly, that of moral obligation is heavenly. Yet it is obvious that if by a source of obligation is meant only a power which binds you or compels you to do a thing, it is not because it does do this that you ought to obey it. It is only if it be itself so good, that it commands and enforces only what is good, that it can be a source of moral obligation. And in that case what it commands and enforces would be good, whether commanded and enforced or not. Just that which makes an obligation legal, namely the fact that it is commanded by a certain kind of authority, is entirely irrelevant to moral obligation. However an authority be defined, its commands will be morally binding only if they are—morally binding; only if they tell us what ought to be or what is a means to that which ought to be. (§ 76 ¶ 1)