These caged wild beasts

(James W. Alexander, "Consolation" 1852)

Spiritual rest is promoted by the mortification of sin.

Sin is the sole cause of all the discord, perturbation,
and misery that there is in the universe. It was sin
that produced the disorderly commotion; it was sin
that tore the heart; it was sin that let loose all the
fierce winds of passion to howl tempestuously over
the mind.

If you catalogue the causes of your discontent, your
restlessness, your unhappiness, your feverish fretfulness,
you will find their names to be such as these:
Pride,
Hatred,
Envy,
Revenge,
Anger,
Lust,
Covetousness,
Fear,
Worldliness.

Until these caged wild beasts are driven
out of the soul, there can be no quietness.

"Therefore, put to death whatever in you is worldly:
 sexual immorality, impurity, lust, evil desire, and
 greed, which is idolatry." (Colossians 3:5)