Clean and feed the mind. Just as soap is necessary to make this external body clean, repetition of the divine name, meditation and smarana, remembrance, are needed to clean the interior mind. Just as food and drink are needed to keep the body strong, contemplation of the Lord and meditation on the Atma are needed to strengthen the mind.
Without this food and drink, the mind will just totter this way and that. As long as the waves are agitating the top, the bottom cannot be seen. When the waves of desire agitate the waters of the mind, how can one see the base, the Atma? The tottering causes the waves and is caused by want of food and drink.
So, clean the mind with contemplation of the Lord. Feed it with meditation on the Atma. Only meditation and sadhana, spiritual practice, can clean the depths of the mind and give it strength. Without purity and strength, the Atma recedes into the distance and peace flees.