"The Constitution is not a mere lawyers document, it is a vehicle of life, and its spirit is always the spirit of the age" -- Dr B.R. Ambedkar

The state is an "independent political entity". It is the largest of all human associations. The state has four essential elements, namely population, territory, government and sovereignty. There are various variations in the population of the state but still, all are related to each other in the name of the state. Everyone knows that this is their kingdom and they have to protect it from external and internal disturbances. We need an armed force to protect the state from external forces and for internal affairs, but in today's world, it is not true that only an army, police or law and order is enough for the state. Every state aspires to be a social welfare state.

The constitution represents the essence of the political system of a country.
When we look at the constitution of any country, we come to know that there is a democracy, dictatorship, monarchy etc. in the country. For example, the old constitution of Nepal shows that there was a monarchical political system but now there is a democratic political system. Now we know that Nepal has a democratic political system but how will the political system work? So the answer is that the constitution also provides guidelines that govern decision making within these cities.

The Constitution provides authority
If there is a state whose population is more than 100 crores, the people cannot join together and work together all the time. It requires basic organs, authorities or equipment to administer as a state. As we can also see in Article 21 of the Constitution of India, "Definition in this part, unless the context otherwise requires, the State includes the Government and Parliament of India and the Government and the Legislature of each of the States and all local or other authorities within the territory of India or under the control of the Government of India"

Now the question is if we need these basic organs or authority then how will we make these authorities and how much power should we give to these authorities. We have to follow a check and balance policy that they should work in their jurisdiction. We have to check that all the powers are to be separated. Like the legislature should not come in the way of the judiciary to create independence of the judiciary. The constitution ensures that all authorities do their work without obstructing others in their work and also ensure that all authorities cooperate with each other.

The Constitution protects us from ourselves.
If we want to make our society successful then we need a constitution. Let us take the example of a cricket match if we play cricket without any rules the bowler can throw the ball from the half-pitch, the batsman can say that I am not out even if a fielder catches the ball. Anything can happen because there are no rules in the game and it will be concluded that the game will not be over or maybe the players harm each other. So we can say that the game will not be successful. 

Similarly, if a state does not have a constitution, there will be no rules and without rules, the society will become like a forest. And the people of the state will harm each other, one person may kill another, whatever the reason may be.

For example, one person may not like the other or one person wants to usurp another person's property. So to ensure that any state becomes a successful country, we need a constitution. The constitution not only gives us some fundamental rights but also tells us about our duties. It teaches us about cooperation, justice, liberty, equality, fraternity, sovereignty, socialism, secularism, democracy and many other things.