Conscience is an inferior light of the Spirit: to do things against conscience is to do them against the Spirit. God spake to me, and I heeded him not. How doth God speak? When conscience speaks, and saith, This is good, this is bad, then God speaks. Conscience hath somewhat divine in it. It is a petty god. It speaks from God. Especially when the Spirit joins with conscience, then God speaks indeed; then there is light upon light.
From Works, A Fountain Sealed