So if he swears, his memory, which has been educated to resent all swearing, brings up at once to his notice the lessons of years.
The same kind of thing is seen on the cricket field. A batsman is playing steadily. He has been trained to play cautiously against good bowling. But he has a favourite stroke. The bowler knows it He sends a ball very aptly called a "ticer" to entice the batsman to hit, in the hopes of a catch. The desire to make that pet cut or off-drive is strong; but the "habit" of caution is stronger; he lets the ball go by. Or the habit is not as strong as the desire, and he cuts the ball; and, even as he watches it flash safely through the field for the boundary, he feels that he ran a foolish risk, and must not repeat it.
What is it tells him he did wrong? It is his memory: his memory, which has been educated to check his rashness. In fact, it is his cricketer's conscience that warns him.
So with the youth who swears. No sooner has the word passed his lips than his educated memory, which has been trained to check swearing, brings up the lesson, and confronts him with it.
But let him swear again and again, and in time the moral lessons in his memory will be overlaid by the familiar sound of curses; the habit of flinching from an oath will grow weak, and the habit of using oaths will grow strong.
It is really what happens with the rifleman who gives way to the recoil and forms a habit of flinching, or with the cricketer who allows his desire to score to overcome his habit of caution. The old habit fades from disuse; the new habit grows strong from use. The rifleman becomes a hopelessly bad shot; the batsman degenerates into a slogger: the young man swears every time he speaks, and his conscience loses all power to check him.
Take the case of the letter "h." The young Lochinvar who comes out of the West sounds his aitches properly and easily—just as properly and as easily as a fencer makes his parries, as a pianist strikes the right notes, as C. B. Fry plays a straight bat. It is a matter of teaching and of use, and has become a habit. From his earliest efforts at speech he has heard the "h" sounded, has been checked if he failed to sound it, has corrected himself if he made a slip.
But the young Lochinvar who comes out of the East drops his aspirates all over the place without a blush or a pang. He has never been taught to sound the "h." He has not practised it. He has formed the habit of not sounding it, and it would take him years of painful effort to change the habit.
Now what happens in the case of a letter "h" is what happens in the case of the rifle, of the ticing ball, of the swearing. One man's memory is educated to remind him not to swear, not to slog, not to flinch, not to drop the "h." The other man's memory is not so trained.
And this trained memory we call conscience. It is purely habit: and it is wholly mechanical.