Now I will tell you what vichara is. Vichara means enquiry. It is an enquiry into the nature of Brahman or Atman. Enquiry of "Who am I?" is also vichara.
What is bondage? What is freedom? What is the relation between the jiva and Brahman? How was this Universe born? Who is the Creator? These constitute vichara.
Vichara leads to Brahma-jnana (realisation of the Infinite).
You are imprisoned in this cage of flesh for a long time on account of your identification with the body. Cut this illusion with the sword of knowledge. "I am the all-pervading Sat Chit Ananda Brahman" - and be ever blissful.
Give up "I ness, mine ness", agency or doership. Become a silent witness. This is wisdom.
Brahman or the Absolute is the only reality. Mind and the universe are unreal. Mind alone is the universe. Action of the mind alone is karma.
Renunciation of egoism and desires constitutes real renunciation. This leads to atma jnana (self-knowledge). Practise Brahma vichara and you will soon attain Self-realisation.
Identification with the body is bondage. Identification with the Atman or soul is liberation.
"I am body", "This is mine", "He is my son", "She is my wife" - this is bondage.
"I am all-pervading immortal soul", "Nothing belongs to me", "All is Brahman" - this is liberation.
If the mind is attached to objects, this is bondage. If it is unattached, this is liberation.
Where there is no duality, there is immortality. When the three knots are cut, one attains immortality.
If your object in life is immortality, shun sense-objects as poison. Where there is nothing to be seen, or heard, or thought of, there is immortality.
Immortality is the very nature of Atman. The road to immortality is steep and thorny. The help of a realised sage is necessary - at every step.