It is an evil thing to empty your mind.

 Let the words of my mouth and the meditation of my heart be acceptable in your sight, O Lord, my rock and my redeemer.

Psalm 19:14 (ESV)
 
"Meditations into which a man puts his heart will prove the spring of action. The depths of this prayer are reached in the petition concerning the meditations of the heart. Meditation is only unuttered speech. We think in words. Yet the words we utter have a separate existence, and most powerfully affect the thoughts of our mind. Language has a reflex influence upon our thoughts. Thought is revealed in speech, but speech reacts upon thought. The Bible is fully alive to the importance of right words." (Biblical Illustrator)
 
Often, good concepts from the Bible are taken and tried by the secular world to profit personally or corporately. Meditation is good if you meditate on God and His Word and reflect about how your life aligns with it.
 
It is an evil thing to empty your mind, for then you are prime to have someone else fill it for you. We must meditate on God's Word day and night, not on nothing.