The natural man does not perceive and
spiritual things, for he is dead to them. Speak
to him about the joys of the spiritual life, and
you will soon discover that you are casting your
pearls before swine- he thinks you a fanatic for
talking such nonsense. He is as dead to spiritual
realities as a mole is blind to astronomy, or a
stone is dead to music.
-Spurgeon, "Death & Life: The Wage & The Gift"