As heat is opposed to cold, and light to darkness, so grace is opposed to sin. Fire and water may as well agree in the same vessel, as grace and sin in the same heart.
You may as soon fill a bag with wisdom, a chest with virtue, or a circle with a triangle, as the heart of man with anything here below. A man may have enough of the world to sink him, but he can never have enough to satisfy him.
'My sin is ever before me' [Psalm 51.3]. A humble soul sees that he can stay no more from sin, than the heart can from panting, and the pulse from beating. He sees his heart and life to be fuller of sin, than the firmament is of stars; and this keeps him low. He sees that sin is so bred in the bone, that till his bones, as Joseph's, be carried out of the Egypt of this world, it will not out. Though sin and grace were never born together, and though they shall not die together, yet while the believer lives, these two must live together; and this keeps him humble.
Oh, is the Lord Jesus Christ a believer's life? Why, then, let no believer be disquieted, nor overwhelmed and dejected, for any loss or for any sorrow or suffering that he meets with for the Lord Jesus Christ's sake. Oh, what should a man then do for Jesus Christ, who is his life!
Let those be thy choicest companions who have made Christ their chief companion.