According to Indian tradition time is divided into four ages. The first age is called Sat Yuga: Sat is truth and Yuga is age so Sat Yuga is the age of truth. The second age is called Treta Yuga and the third is called Dwapar Yuga. The final age in which we are at the moment is called Kali Yuga.
Kali Yuga started some 6000 years ago and lasts for 432,000 years. Dwapar Yuga lasts twice as long, Treta Yuga lasts 4 times as long and Sat Yuga 8 times as long. The four yugas combined are one day of Brahma. After Kali Yuga has finished comes a long period of rest which is one night of Brahma. One day and one night of Brahma combined last about 8.6 million human years. And then a new cycle starts: Sattva yuga, Treta yuga, Dvapar yuga, and Kali yuga and then again and again and again.
In Sat Yuga people were very honest; the whole earth was Mother Earth and all people were family. There was no struggle for life. There was enough time to think good, make laws of conduct, write scriptures and do good things. In Treta Yuga people were honest but Earth did not provide enough food and clothing so they had to spend efforts for it. In Dwapar Yuga the number of people increased, business increased, more territory, more boundaries and small kingdoms started. Then started the final phase which is now, Kali Yuga, the dark age, where small pieces of land have become independent countries. Like Holland, Belgium and England are all very small kingdoms with their own character and their own language. In the Kali Yuga this individualistic feeling increases.
In our society the moral laws are losing their value. People born fifty years ago say that the world has changed a lot and for people born a hundred years ago the world is completely different.
Moral decay: the bull of dharma
Everybody has some natural obligation and this natural obligation is dharma. Dharma is practicing truth in a gentle way. Some therapists and docters don't mind telling you the truth even if it disturbs you much. Sometimes people lie to make others feel good; like when they say "Oh I am so happy to see you!" it is a lie only to please somebody. Or the plastic smile of an airhostess in an airoplane even when she is angry; that also is should not be done. On the one hand you should be considerate with others but on the other hand you should allow yourself the freedom to express your feelings. Dharma is living without violence in words, thoughts, and deeds. Maybe you can avoid violence in deeds, but sometimes words become violent, or violence enters your thoughts. To get free from violence in deeds, words and thoughts is the essence of Hindu religion, Sanatan Dharma.
Dharma is becoming selfless. There is nothing more against dharma than harming or disturbing other people. Harming others and creating problems for others is guided by selfishness. There is no higher dharma than helping others, thinking about the welfare of others and service to humanity.
Precisely defining dharma is difficult because situations can be ambiguous. In some tribes it is a holy worship to kill a man and sacrifice the body whereas morally and ethically it is a crime. The practice itself is very much against dharma but when it is tradition in that society the followers are not breaking dharma. Violence is really violence when it is done for selfish motives. If you eat a chicken when also fruits and other nice foods are available then you are eating the chicken only for the taste and you are doing something bad. But when you are starving and there is no other food available then it is your dharma to save your life and kill the chicken and eat it. You can eat it to save your life but not for luxury. Sometimes being passive is breaking dharma more than fighting. Like when you see that social injustice is done then you have the obligation to resist and it may imply that you pick up weapons; not for revenge, not because of hatred but to defend justice.
Dharma is represented as a bull because a bull ploughs the fields and helps human life for just a little hay. The bull is a most humble servant and a good friend of man. He helps us and makes our loads light.
In Sat Yuga the bull of dharma stands comfortably on four feet very well without falling down. Following dharma is normal. Promises are kept and if anybody dares to break his promise people make a big fuzz of it. In Treta Yuga the bull stands on three feet. When standing on three feet, keeping balance is not difficult. People are a little selfish and it is no problem to break a promise once in while. In Dwapar Yuga the bull has to stand on two feet; that is easy for humans and penguins but not for bulls. So the bull of dharma performs his balancing act like a clown in a circus. Selfishness increases and breaking your promise becomes acceptable. And in Kali Yuga the bull of dharma stands on one foot. So it becomes very difficult to follow dharma in Kali Yuga. Only exceptional people follow dharma and are true to their words.
Ancient and modern warfare
In the previous yuga wars were different. People fought man to man duels, always at armlength distance, following particular laws. Old people, women, children, and sick people were never attacked. A huge area was selected in the countryside where people from both armies would gather. They would stand on two sides and they could see eachother. Spies would go to the king and his commanders and introduce the opponents saying "There on that chariot with these horses and that kind of flag stands this person from that family." All fighting occurred only during the day. It was not done to attack the enemies' camp at night. At night people could visit the camps of their enemies and help them to recover from their injuries. They did not fight their enemies because of hatred but because of principle, because of ego problems.
When gun powder came wars became different everywhere in the world. Suddenly you had the power to hit from a distance without being seen. This made wars more destructive and cruel. Sometimes many countries combine their military and technical power against a small country and do carpet bombing, destroying all resources and creating havoc. And when the war is won they make a contract to rebuild the country for a hundred million dollars. Previously that kind of war did not exist. It could only happen in Kali Yuga.