Swami Sivananda

Just as gold is purified by heating it on the fire, so also mind is purified by the fire of meditation.

As fire is concealed by ashes, sword by the scabbard, sun by the clouds, foetus by the amnion, rubies by the earth, mattress by the bedsheet, so also Brahman is concealed by flesh and bones. If you remove the ash you can perceive the fire; if the clouds are dispersed you can cognise the sun; if you remove the scabbard you can behold the sword; if you remove the bed sheet you can see the mattress. Even so, if the veil of ignorance which conceals the Brahman is removed by knowledge of Brahman you can directly cognise the self-luminous Brahman.

You cannot see the all-pervading butter in the milk, but if you churn it you can get the butter. Even so you cannot see Brahman by these physical eyes, but you can behold the all-pervading Brahman by the churning of meditation.

Purge your mind of all impurities. Sever mentally all your connection with visible objects. Destroy the weeds of desires. Abandon all sankalpas (thoughts). Eradicate the longings. Meditate on Brahman. You will attain soon the nondual Brahmic seat of ineffable splendour.