“Your mind can be compared to a glass of muddy water. If you let the glass stand for a long time, the mud will settle at the bottom of the glass and the water will become fairly clear. So when you sit down for a while to concentrate, your mind is muddy with restless thoughts. But if you sit long enough, repeatedly bringing the wandering mind back to the practice of meditation, you will see that all thoughts settle down; and in that stillness you will feel superconsciousness.” — Paramahansa Yogananda
Our minds are filled with muddy impressions of who we think we should be. We absorb distorted beliefs, like detritus, and allow them to influence us. A lot of times we even define ourselves by this garbage without thinking clearly.