A series of quotes and extracts from Cardinal Newman's work focussing on conscience and conversion.
“Well,” she said, “I feel that God within my heart. I feel myself in His presence. He says to me, ‘Do this: don’t do that.’ You may tell me that this dictate is a mere law of my nature, as is to joy or to grieve. I cannot understand this. No, it is the echo of a person speaking to me. Nothing shall persuade me that it does not ultimately proceed fro m a person external to me. It carries with it its proof of its divine origin. My nature feels towards it as towards a person. When I obey it, I feel a satisfaction; when I disobey, a soreness—just like that which I feel in pleasing or offending some revered friend.
Conscience is not a long-sighted selfishness, nor a desire to be consistent with oneself; but it is a messenger from Him, who, both in nature and in grace, speaks to us behind a veil, and teaches and rules us by His representatives. Conscience is the aboriginal Vicar of Christ, a prophet in its informations, a monarch in its peremptoriness, a priest in its blessings and anathemas.
The Christian’s faith and obedience are not the same religion as that of natural conscience, as being some way beyond it; secondly, [I say] that this way is “not far,” not far in the case of those who try to act up to their conscience; in other words, that obedience to conscience leads to obedience to the Gospel, which, instead of being something different altogether, is but the completion and perfection of that religion which natural conscience teaches … what conscience suggests, Christ has sanctioned and explained; to love God and our neighbour are the great duties of the Gospel as well as of the Law; he who endeavours to fulfil them by the light of nature is in the way towards, is, as our Lord said, “not far from Christ’s kingdom;” for to him that hath more shall be given.