A furious beast

(Thomas Boston, "Human Nature in its Fourfold State")

"Their throats are open graves;
 their tongues practice deceit.
 The poison of vipers is on their lips.
 Their mouths are full of cursing and bitterness.
 Their feet are swift to shed blood."
    Romans 3:13-15

The body itself also is partaker of corruption and defilement.
Therefore the Scripture calls it sinful flesh, Romans 8:3. The
natural temper, or rather distemper of our bodies have a natural
tendency to sin. The body incites to sin, betrays the soul into
snares, yes, is itself a snare to the soul. The body is a furious
beast, of such a temper, that it will not be beat down, kept
under control, and brought into subjection. It will cast the
soul into much sin and misery.

The body serves the soul in many sins. Its members are weapons
of unrighteousness, whereby men fight against God. The eyes and
ears are open doors, by which impure motions and sinful desires
enter the soul. The tongue is "a world of iniquity," "an uncontrollable
evil, full of deadly poison;" by it the impure heart vents a great deal
of its filthiness. The throat is "an open grave." The feet run the
devil's errands. The belly is made a god, Phil. 3:19, not only by
drunkards and riotous livers—but by every natural man. So the
body naturally is an agent for the devil, and a storehouse of
weapons against the Lord.

To conclude: man by nature is wholly corrupted, "from the sole of
the foot, even unto the head, there is no soundness in him." As in
a dunghill, every part contributes to the corruption of the whole,
so the natural man grows still worse and worse—the soul is made
worse by the body, and the body worse by the soul; and every
faculty of the soul (the mind, will, affections, conscience and
memory) serves to corrupt another more and more.