It is universally acknowledged that nature has divided the eternal time into four eras or yugas — Satyug, Tretayug, Dwaparyug and Kalyug, which is the present era. As per the laws of nature, Satyug - the Golden Era, is definite to follow Kalyug. Therefore, it becomes necessary for all of us to enlighten ourselves about the Golden Era and become competent to mould ourselves accordingly.
The basic difference between the beings of Satyug and Kalyug is that the foundation of the character of beings of Satyug is based on absolute spiritualism, Truth and knowledge of the Self, which helps them retain purity of thoughts at all times. The basis of this is firmness in the practice of Equanimity and Even-Sightedness.
However, with deterioration in the level of commitment to humane values, the basis of character of every being in Kalyug becomes purely materialistic with me and mine as the basis of living which is the root cause of every evil in the world. This mires the mind in lust, anger, greed, pride, attachment etc. Ego, selfishness and negative thinking become the foundation and objective of survival.