This is the state of mind of the major portion of the Silver Age people. With this outward-looking of their mind begins the hunting for Absolute Happiness on the surface of life, instead of in its deepest depth where it dwells. This search for it through material pleasures ends in this real object of that search being lost from their view and the pleasures themselves taking its place. This last stage of mental degradation is not true, however, of all the people of the age. A small portion still retain much of the high spirituality of the Golden Age. Some are swayed by predominant Rāja, others are ruled by Rāja and Tama, while others are covered almost entirely by Tama. This leads to the division of the people into castes. Those who are uninfluenced by the assertive Rāja are called Brāhmans; those swayed by Rāja are called Kshatriyas; those by Rāja and Tama are called Vaishyas; those mostly ruled by Tama are called Sudras. I have treated the caste system at some length in the next section. Tastes for material comforts involve housekeeping, and housekeeping is impracticable without a house. The people therefore build houses to live in for the first time in the Degeneration period of the Satya Yuga. The Tretā is called the Silver Age because gold, the spiritual metal, becomes less abundant with the decrease in spirituality in Nature, and silver is found in abundance. People in the Satya Yuga use gold for household utensils, hence the Satya Yuga is called the Golden Age. The period in which gold plates come into use does not belong to the Golden Age proper. It is used in what is called the Degeneration (Sandhyāngsa) period of the Golden Age. Every Age has a Junction period and a Degeneration period, called in the Hindoo Scriptures, the Twilight Periods. These periods are of equal length. The morning Twilight period of the Satya Yuga is 400 divine years, equal to 144,000 lunar years. Of the same length is its evening Twilight period. The morning Twilight period represents the Junction period, the junction between the previous Kali and the Satya Yugas. The evening Twilight period may be called the degeneration of the Satya Yuga. It is in this degeneration period covering 144,000 years, that Rāja asserts itself and people begin to turn to material pleasures, build houses, wear clothes, take to housekeeping, eat cooked food and generally use gold plates, gold being abundant and on account of its possessing pure (spiritual) magnetism, purer than that of other metals.