Simultaneously with the introduction of the Caste System in the Silver Age are instituted the Four Stages of Life, the object of which is to help the lower state of human consciousness to gradually attain to the highest spiritual realization. They are graduated processes of mental and physical application and discipline by the practice of which individuals are to recover the absolute illumination, being and bliss enjoyed by all human souls in the Golden Ago. They impart a scientific training to the human mind in order to enable it to subdue its Rājasic (active) and Tāmasic (darkening) attributes by developing the Sāttwic (illuminating) attribute through concentration upon the Basic Principles of Life—the Centre and Essence of Absolute Purity and Illumination. The first stage is called Brahmacharjya or spiritual Pupilage. The second stage is called Grihastha or Householdership. The third stage is called Vānaprastha or Asceticism, The fourth stage is called the Bhikshu or Wandering Friarship. The first, third and fourth stages are enjoined for the three twice-born castes and the third and fourth are open even to a Sudra if he is found worthy of adopting them. The Brāhman, Kshatriya and Vaishya are called twice-born; the first birth is the physical birth, the second is the spiritual birth through the investiture of the holy thread from which begins the performance of daily spiritual duties and practices. The first stage of life begins, soon after this spiritual initiation, at the age of twelve, when the boy goes to reside with the Gooroo (spiritual guide) for studying the Veda and for undergoing spiritual, mental and physical discipline. The Gooroo is an illuminated Brāhman sage whose love and affection for the pupils in his charge and anxious care and efforts for the unfoldment of their souls are not equalled by those of even their parents. He feeds, clothes and lodges them in his own abode free of any charge or consideration whatever. His one thought and concern is to help them to realize the Truth, to be freed from the bondage of matter and thus enter the Absolute Realm of Eternal Love and Happiness. While every student has to perform the same regular spiritual rites and practices and to say the prayers daily after physical purification, the method of training adopted by the Gooroo for developing their soul is not the same in each case. To some he explains the truths of the Veda and asks them to meditate on their meanings. Others, who show natural instincts of devotion, he trains into practical realization of the same truths without teaching them a single word of the Veda.