To look for the God without, abandoning the God within, is like going in quest of conch-shells after giving up the precious diamond on the hand. If you cannot find Him in your heart you will not find Him anywhere else. Search Him within the innermost recesses of the heart. He is subtler than the subtlest. Make the lotus of your heart as pure as possible. Withdraw the fuel of desires and extinguish the fire of Sankalpas. Realise the Truth now through your higher mind. Enjoy the perennial joy of Divine Bliss.
A rich man keeps his valuable jewels in an iron safe that is kept in the innermost chamber of his bungalow. One has to pass through five compartments before he reaches the compartment in which the iron safe is placed. Five walls screen the iron safe. Even so this most valuable jewel of the Atman is placed in the innermost recesses of your heart. Five veils cover this Atman. The five veils are the Annamaya, Pranamaya, Manomaya, Vijnanamaya and the Anandamaya Kosas. You must tear these five veils if you want to approach the Atman. In other words, you will have to pass through the five compartments formed by the five Kosas if you want to get at the jewel of the Atman.
An extract from Meditation on OM and Mandukya Upanishad by Swami Sivananda