However, this doesn't mean that authority doesn't count. In fact, authority does often prescribe laws in many cases, but the laws are only instrumental towards a much larger cause. Thus, we have law-givers such as Solon, Moses, and Manu. However, the validity of the prescriptions are based on a deeper intent. The intent or the spirit of the law is what matters. It also means that where laws fail to serve the intent, they must fade away and give place to the new.
Plato's elaborative study of justice as an ethical virtue in the analogically larger Republic is based on the same understanding that ethics and politics are inseparable. Similarly, his disciple Aristotle didn't see any reason to separate the both. In the Biblical tradition, the entire Mosaic Law was based on the Decalogue or the Ten Commandments, which were the essence of the Law. Jesus pointed out that they all hung on the two Great Commandments: To love God absolutely and to love one's neighbor as oneself. Of course, Paul, later submitted that the Law was only a revealer and a restricter. It revealed human sinfulness and it was meant to restrict the lawless (it was given for the lawless). Jesus pointed out that certain laws (for instance, the law of divorce) were only permissive because of the hardness of human hearts, but didn't reflect the original intent of human creation.
Looking, now, into the Indian Constitution, one asks what is Indian Law based upon ultimately. The Preamble makes the democratic nature of the Republic clear. And, so it is the people's government for sure. But, the moral philosophy is indicated in words like "humanism" and "scientific temper", featured later on under Fundamental Duties. While the temper is scientific, the philosophical ground is humanism and its philosophy of man is condensed in the section called Fundamental Rights. The Law exists to ensure the protection of these fundamental rights of every Indian citizen. Consequently, any law that is inconsistent with these rights is automatically annulled.
The Fundamental Rights are not prescriptions to the people but declarations of humanism. These declarations are prescriptive only to the laws, since the laws are expected to conform to them. Thus, they not only inform but also serve as reference points, as absolute foundation, for the laws. As such, we may refer to them, with regard to humanism, as the intent, or spirit of the laws; perhaps even as the Law of the laws since they serve as the measure of all laws.
But, how do we know that these declarations are true? Perhaps, it is similar to asking about the laws of logic, "How does one know whether they are true?" The answer is: by using them or trying not to use them. One cannot deny them, but then one cannot deny anything without using them. Similarly, one cannot deny the Fundamental Rights without himself losing the rights.