(5) The fifth is the manual, the pocket-book, the bosom-book of our conscience. The other books will manifest what we should have done; this, what we have done. We cannot except against it, because it hath always been in our own keeping, and nothing shall be written in it, but what is subscribed by our proper hand.
It hath three offices: first, to give in testimony of something acted or omitted. Secondly, to examine whether the action or omission were lawful or unwarrantable. Thirdly, to give judgment according to that evidence.
It can both bind and loose; it binds a man faster than the Philistines bound Samson, and looseth him sooner than the angel loosed Peter. It is a private law within man : when law and chancery too have done with him, (and that not seldom is long before it hath done with him,) then conscience taxes him in hand. It is a true looking-glass, that represents all blemishes, without favour or flattery. It is below God, but above man, a vice-god ; and deals with us here, as God will do hereafter. There is a bill framed out of the law, it is high treason against our high Sovereign's crown and dignity: our works are the evidence, and conscience is the witness, which will not be bribed to give a false testimony.
If the main course of our life be gracious, and our conscience will speak for our works, that they proceed from a sound faith and honest heart; we are then quit by proclamation, for nobody comes in against us: the world may not, our sins shall not, our conscience must not, the angels dare not, God will not, the devil cannot, for he is the father of lies, and his word will not be taken.
But if otherwise, all these will be against us: there need no subpoenas to fetch in witnesses; they come unsent for, and cannot be kept back; they will speak the truth, and all the truth. As intelligencers for statesmen mingle themselves with all companies, but use their best art to keep themselves concealed; so the conscience is God's informer, a spy in the soul, mixing herself with all our thoughts and actions: it is indeed the reflection of the soul upon itself. Though we know not what this conscience is, yet this conscience knows what we are. As Pilate asked Christ, What is truth? John xviii. 38, when the Truth stood before him; so many ask what is conscience? when indeed conscience is within them.
Exposition of 2 Peter, 670