Charles H. Spurgeon on Psalms 46:10

Be still, and know that I am the Lord. Not everyone is a fit scholar for God's school, but such as are purified according to the purification of the sanctuary. Carnal men are drowned in fleshly and worldly cares, and neither purged nor lifted up to receive the light of God, or else indisposed by prejudice or passion, that they cannot learn at all. We will never savingly know him, till our souls be free of these indispositions. Among all the elements the earth is fitted to receive seed of the sower; if he cast it into the fire, it burneth; if in the air, it withereth; if in the waters, it rots, the instability of that body is for producing monsters, because it closes not straitly the seeds of fishes. Spirits of a fiery temper, or light in inconstancy, or moving as waters, are not for God's lessons, but such as in stayed humility do rest under his hand. If waters be mixed with clay in their substance, or their surface be troubled with wind, they can neither receive nor render any image; such unstable spirits in the school of God lose their time and endanger themselves. William Struther.