What is it? What is conscience? Conscience is chiefly habit: it is chiefly memory: but it is partly, perhaps, inherited instinct. Conscience is habit. We all know that it is easier to do a thing which we have often done before than to do a thing we have never done before.
We all know that what we call practice improves an organ or power of our body or our mind.
As the proverbs put it: "Use is second nature." "Practice makes perfect."
Most of us know that an organ develops with use and decays with disuse.
If you wish to develop your muscles you must use them. If you wish to improve your memory or to sharpen your wits you must use them.
When a man is first taught to use a rifle he finds to his surprise that he cannot pull the trigger just exactly when he wants it. But in time he does that quite without thought or effort. The muscles of his finger have been "educated" to act with his eye.
Some men, when they first begin to shoot, shrink from the rifle. They fear the recoil or the sudden explosion, and the muscles of their shoulder flinch. If a man gives way to that habit it grows upon him, and he can never shoot straight. The muscles have learnt to flinch; and they flinch.
One man falls into the habit of swearing. The habit grows upon him. The words come ever more readily to his tongue, and he swears more and more.
Now, let us suppose a boy has been taught that it is wrong to swear. In his memory lies the lesson. It has been repeated until it has grown strong. When he hears swearing it shocks him. But the more he hears it the less it shocks him. The words grow more familiar to his ear, just as the sound of a waterfall or of machinery grows familiar to the ear.
Then suppose he swears. That is a very unusual act for him. And his old lesson that to swear is wrong is still firm and ready. It is not his habit to swear: it is his habit to shrink from swearing.