by Spurgeon-

God does not promise that He will improve our nature,
or that He will mend our broken hearts. No- the promise
is that He will give us 'new' hearts and right spirits.

Human nature is too far gone ever to be mended--
It is not a house which is a little out of repair, with
here and there a slate blown from the roof, and here and
there a piece of plaster broken down from the ceiling.

No; it is rotten through-out; the very foundations have been
sapped; there is not a single timber in it which is sound; it is
all rottenness from its uppermost roof to its lowest foundation,
and ready to fall. God does not attempt to mend it. He does not
shore up the walls, and repaint the door; He does not garnish
and beautify, but He determines that the old house shall be
entirely swept away, and that He will build a new one.

It is too far gone to be mended. If it were only a little out
of repair, it might be restored. If only a wheel or two of that
great thing called "Manhood" were out of repair, then He who
made man, might put the whole to rights; He might put a new cog
where it had been broken off, and another wheel where it had
gone to ruin, and the machine might work anew.
But no; the whole of it is out of repair; there is not one lever
which is not broken; not one axle which is not disturbed.

"The whole head is sick, and the whole heart faint. From the
sole of the foot unto the head, there is no soundness in it;
but wounds, and bruises, and putrefying sores."

The Lord, therefore, does not attempt the repairing of
this thing, but He says, "A new heart also will I give you,
and a new spirit will I put within you."