You must try to maintain a deep peace in yourself and not allow yourself to become troubled. Ask Jesus to command the winds and the storms and bring about calm and tranquility in [your] inner life. The world cannot give peace. Jesus the Lamb of God has come so that we may have it abundantly.
But of course we shall only have perfect peace in heaven. Here below where we are only in transit, we must keep aspiring to that peace which awaits us in the arms of God. One day we shall fall asleep and rest, as the Psalmist says, in Him who Himself is eternal peace.
Servant of God Hermann Cohen
Fr. Augustine-Mary of the Blessed Sacrament, O.C.D.
Servant of God Hermann Cohen
Various spiritual counsels
Tierney, T 2017, A Life of Hermann Cohen: From Franz Liszt to John of the Cross, Balboa Press, Bloomington, IN
Carmelite Quotes 
The Sleep
Elizabeth Barrett Browning – 1806-1861 would be well worth googling. It’s a beautiful exposition on God giving us deep rest which comes only from Him. This beautiful passage here reminds me of it.
We may just have to investigate that!