"The lowest orders must be what they are. A primrose can never be a tomcat, but man has no 'must' imposed upon him; having an intellect and free will, man merely ought to do something. That 'oughtness' is recorded in conscience.
Each of us has the power to regulate something outside of us, for example, to throw a shoe at a screeching cat at midnight. But we also have the power to regulate something inside us, namely, to determine our character. Many things happen to us, but what is more important is what we make happen to ourselves. We are self-determining creatures, unlike frogs and stones.
Everyone appeals to a standard of conduct, even though he denies it. Half man's life is spent in telling himself what he 'ought' to do or his neighbor what he 'ought' to do. Ants never say, 'Get in line;' pigs at a trough never say, 'Wait your turn;' bears never growl to other bears, 'You would not want me to do that to you.' Only humans use the argument, 'Yes, but I saw it first.' There is no sense in saying anything is wrong unless we know what is right. No referree could call a foul in basketball games unless there were rules.
This 'oughtness' in us, which is not mechanical, or biological, or instinctive, but rational, implies a standard. Conscience puts before us certain principles to guide our actions. Conscience itself needs help, but we are not going to discuss that here. We are all born with the power of speech, but we need grammar. Conscience, too, needs Revelation."