It is the knowledge that the Atman is the only permanent entity all other things being only ephemeral. If this knowledge is not there, man will always remain a samsAri and continue to suffer as he does now.
The basic conviction that ‘everything that gives us pleasure in this world, that gives status and honour, all of that is impermanent; nothing will ever give us permanent happiness; what gives permanent happiness is only the Atman, the only permanent entity’ – this faith is the most important thing.
Now and then the mind may be distracted and drawn towards several other things. At every such time one should beware and keep the mind steady.
“Should I go into this just because it gives me pleasure? Is this an unmixed happiness? Even if it be unmixed happiness, will it be permanent? Once the mind enters into it will not the taste of it entice it to make efforts to go into it again and again? Would that not be a bondage of the mind? If something will not help the mind to become pure and restful, should I enter into it?”
Such analysis has to be done by the intellect. It should keep weighing the pros and cons about what is permanent and what is impermanent. Only then can we hope to go the spiritual path.
This balancing analysis by the intellect is called ‘vivekaM’. The analysis of balancing between what is permanent and what is ephemeral is called *nitya-anitya-vastu-vivekaM*. This is the very first step of Atma-SAdhanA.