A slothful spirit is an impediment to a heavenly life, and I verily think there is nothing hinders it more than this in men of a good understanding. If it were only the exercise of the body, the moving of the lips, the bending of the knee, men would as commonly step to heaven as they go to visit a friend. But to separate our thoughts and affections from the world, to draw forth all our graces and increase each in its proper object, and to hold them to it till the work prospers in our hands—this, this is the difficulty.
Sloth, indeed, does affect ease and quiet, but by affecting them does lose them; it hates labor and trouble, but by hating them does incur them. It is a self-destroying vice, not suffering those who cherish it to be idle but creating much work and multiplying pains unto them; engaging them into diverse necessities and straits which they cannot support with ease; and out of which, without extreme trouble, they cannot extricate themselves.
Now these three things are in a treasure: that which a man loves most and sets the highest price upon and that to which his heart doth retire and seek supply from in all his wants; and every man must be supplied out of his treasure, that I will tell you. Take a rich man when he comes to die, riches avail not in the day of wrath. Therefore God only is the saint's treasure and chief good; he lays up treasure in heaven and this treasure is God.
What is conversion? It's the change of a man's treasure, of a man's chief good. Till thou change thy chief good, it's in vain to complain of the disorders of thy heart; therefore, every unregenerate man may hence see the absolute necessity of conversion.