The Crest Jewel of Wisdom verses 18-20
From The Crest Jewel of Wisdom
 The wise speak of four items of discipline. Only if these are present can a person become permanently established in reality, otherwise not.
 The first qualification is discrimination of the permanent from the impermanent, then an attitude of detachment towards the enjoyment of all rewards in this life or in lives to come, then the six-fold spiritual wealth con-sisting of inner control and the rest, and finally deep desire for liberation.
 Discrimination of the permanent from the impermanent is said to be the conviction ‛The Absolute is real and the world illusory’.
Commentary: The first mental equipment that a disciple has to have and to cultivate is discrimination (viveka). To discriminate in daily life between what is fugitive and what is real, to evaluate the unreal and
the real, and to give only as much attention to the unreal as will enable us to pursue the real—this is discrimination.
There are two kinds of things in this world, passing and permanent. Everything which is compound has a transitory existence. In the Bhagavad Gita (2.28) the Lord says that is called unreal which does not exist in the beginning and the end, and has only existence in the middle. Why is a dream unreal? Because it has only a temporary intervening existence.
What is ‛real’? The religious man calls reality God, a yogi calls it Self, the scientist calls it truth. Reality is the substratum of all so-called facts. The pyramids exist, Rome existed, Carthage existed; what is common to all? Existence. Will existence ever be destroyed? No! If you imagine that there is nothing before you and you say that nothing exists, still you who make that statement exist. When you know existence, then you know God. Dr McTaggart comes to the same conclusion, that the cognizer, or perceiver, is real. When children chase after a rainbow we laugh, but are not our little ambitions as impermanent as a rainbow? Do not our dreams end suddenly? To understand this is discrimination.
If we devote our life from morning to evening to perishable things, we are called ignorant; for their knowledge brings no satisfaction. We cannot know God unless we cultivate discrimination (viveka); the holy Lord said: ‛Leave all and follow Me’. Turn your back on the perishable and follow reality, the Light of the world. Every faculty grows when exercised and deteriorates when not used. Let us exercise this faculty of discrimination (viveka). You will say: ‛How can we pursue that which is real?’ Yoga is the answer. By prayer, inner silence, renunciation and universal love we pursue what is eternal.