Frank J. Wilstach, comp. A Dictionary of Similes. 1916.
Many men carry their conscience like a drawn sword, cutting this way and that, in the world, but sheath it and keep it very soft and quiet, when it is turned within, thinking that a sword should not be allowed to cut its own scabbard. Henry Ward Beecher
A fly or dust shows itself at once in milk; so in a pure conscience, any, the smallest stain, cannot be hid. And, as a fly is quickly cast forth by any one who is drinking milk, so the busy fly of impure thought is cast from the pure conscience. Saint Bonaventura
He that has a scrupulous conscience is like a horse that is not well wayed, he starts at every bird that flies out of the hedge. A knowing man will do that which a tender-conscience man dares not do by reason of his ignorance, the other knows there is no hurt: as a child is afraid to go into the dark when a man is not because he knows there is no danger. John Selden