Every thing material undergoes change. Nothing can remain the same. Today merges into tomorrow. Any thing which undergoes change can not be Truth. Truth must remain as Truth, in the past, present and future. Now, the world and all objects of nature are constantly being subjected to change – building up or breaking down, evolving or mutating, flowing or festering, growing or dying. How then can it be true? So, there must be some thing stable and permanent and eternal as the background, the base, the foundation, for this changing scene to appear on. Appearance is untrue; reality is eternal.
(From : Sai Veda, The Word of God, sayings of Bhagavan Sri Sathya Sai Baba)