Four ages explained by Maskeen ji

According to Maskeen, a famous spiritual speaker, the four ages considered under Eastern philosophy can be explained not only in terms of Time but also in terms of a person's goal and ambition in a particular point in life.

Guru Nanak explains in 'Asa Di War'
Sat yuga rath santokh ka
Satyug is the truthful stage when contentment is prominent in life.

Maskeen explains that within one age, different people are in different stages. When the majority of population is in a particular stage, then that time can be classified as of that Age.

If the mission is to attain more wealth and the person is not satisfied with what material wealth he has, then he is living in the Kal yuga, the dark age. The Age that is run by falsehood and deceit. If the majority of people are living in this state of mind then its the age of Kalyuga. But while living in this age there are people who have a goal and motivation that coinsides with one of the other ages. Therefore they are living in a different age.

Maskeen also classifies a persons age into four stages. First stage is the unborn child in a womb, 2nd stage is childhood, then middle age and then old age.

Sikiwiki explains the following at http://www.sikhiwiki.org/index.php/Asa_di_Var

O Nanak, the soul of the body has one chariot and one charioteer.
In age after age they change; the spiritually wise understand this.
In the Golden Age of Sat Yuga, contentment was the chariot and righteousness the charioteer.
In the Silver Age of Traytaa Yuga, celibacy was the chariot and power the charioteer.
In the Brass Age of Dwaapar Yuga, penance was the chariot and truth the charioteer.
In the Iron Age of Kali Yuga, fire[unfulfilled desire] is the chariot and falsehood the charioteer. ||1||