The fourth (and last) volume of discourses, or sermons, on several scriptures

Fifthly,¹ If you would keep your Consciences clear, then set a strict Watch and Guard upon your selves, both upon your inward and upon your outward Man. Set a Guard to your Heart, and to all the Approaches to your Heart.

1. 15. Set a strict Watch and Guard upon your selves.

1. Keep a narrow Guard upon your Heart. ¹The Heart is the great meeting Place, where Objects, Thoughts and Affections do swarm and crowd together: And as much Concourse leaves Dirt behind it upon the Place, so this great Heart-Assembly usually leaves it foul and polluted. Our Saviour, Mark 9. tells the Jews, That it was that which was within them, that Wickedness which lay latent in their Hearts, that which proceedeth from the Heart that defiles the Man. There is a Defilement in the Thoughts and in the Desires, as well as in the more gross and bulky Sins of the Life: Hence the Prophet Jeremiah speaks, Jer. 4.14. O Jerusalem, wash thine Heart from Wickedness! Why wherewith is it polluted? Why the next Words show it; How long shall thy vain Thoughts lodge within thee? Vain Thoughts leave a Stain and Contagion ⟨p. 380⟩upon the Soul; and certainly if a vain Thought, that is such a fleeting and volitary Thing, breaths a kind of Contagion and Taint upon the Heart, they certainly then must have foul Hearts indeed and their Spots in Grain, who lie soaking and stewing themselves in Unclean, Malicious and Covetous Thoughts and Designs. Since then that Conscience is apt to receive Taint, but with the breathing of a vain and sinful Thought upon it, how doth it concern us then to keep a watchful and circumspect Eye over every Motion of our Hearts? It is the wise Man's Counsel as you have heard; Keep thy Heart with all diligence, for out of it are the Issues of Life. Look to it, therefore, that you suffer not your Hearts to be defiled with sinful Thoughts or sinful Affections, by those inward and invisible Corruptions that settle at the bottom of it; though the Life be never so clear and crystal, yet if that Mud be but stirred and raised, Conscience becomes thereby defiled and an evil Conscience. And therefore the Apostle,