Sadhanacatustaya is the four means to liberation and prerequisites for studying Vedanta. Sadhanacatustaya includes nityanityavastu vivekah (discrimination between the eternal and the non-eternal entities); ihamurtrarthaphalabhogaviragah (detachment from the enjoyments in this world or beyond), which are the results of previous deeds; samadisatakasampatti (six virtues such as control of mind, etc.); and mumuksha (the desire for liberation).
Nityanityavastu vivekah – The eternal entity is Brahman (Highest Reality) because it is the cause of the universe and is swayambhu (self existent); on the other hand, the world is the effect of that highest Reality. An effect has an end. So the world is non-eternal. One should understand the difference between the two and behave accordingly.
Ihamurtrarthaphalabhogaviragah – Having known to discriminate between eternal and non-eternal entities, a person should practice detachment. All enjoyments are the results of past deeds and are transient. Because they are unreal, it is futile to desire them. Secondly, they are also the cause of the cycle of birth and death. For becoming free from them, detachment is essential.
Samadisatakasampatti – Sama (controlling the mind), containing dama (sense organs), refraining from uparati (ceremonial acts), titiksha (endurance), shraddha (faith in Vedas and in the guru), samadhana (composure). The mind has to be turned away from undesirable objects and for this one has to withdraw dama from worldly objects. By these two, the mind is purified. By observing the third one, uparati, a person becomes an introvert. Titiksha is tolerance of opposites such as hot and cold, pleasure and pain, loss and gain. Shraddha in the guru and Shastras provides samadhana.
The last prerequisite is mumuksha. If the seeker is not very keen on liberation, the other requisites are not relevant. The nature of the Self is real and eternal. Due to avidya (nescience), he finds himself samsari (transmigratory). Freedom from the clutches of nescience is liberation. So this should be the aim of life.
The order of these prerequisites is also important. Unless the aspirant discriminates between the real and the unreal entities, he would not be detached from the pleasures of this world, which are unreal and perishable. Without these two he would not understand the necessity for the six-fold virtues and liberation will continue to elude him. To avoid this, sadhanacatustaya should be followed.