Be very careful to whom you trust one of these keys of the side-door. The fact of possessing one renders those even who are dear to you very terrible at times. You can keep the world out from your front-door, or receive visitors only when you are ready for them; but those of your own flesh and blood, or of certain grades of intimacy, can come in at the side-door, if they will, at any hour and in any mood. Some of them have a scale of your whole nervous system, and can play all the gamut of your sensibilities in semitones, --touching the naked nerve-pulps as a pianist strikes the keys of his instrument. I am satisfied that there are as great masters of this nerve-playing as Vieuxtemps or Thalberg in their lines of performance. Married life is the school in which the most accomplished artists in this department are found. A delicate woman is the best instrument; she has such a magnificent compass of sensibilities! From the deep inward moan which follows pressure on the great nerves of right, to the sharp cry as the filaments of taste are struck with a crashing sweep, is a range which no other instrument possesses. A few exercises on it daily at home fit a man wonderfully for his habitual labors, and refresh him immensely as he returns from them. No stranger can get a great many notes of torture out of a human soul; it takes one that knows it well,--parent, child, brother, sister, intimate. Be very careful to whom you give a side-door key; too many have them already. --You remember the old story of the tender-hearted man, who placed a frozen viper in his bosom, and was stung by it when it became thawed? If we take a cold-blooded creature into our bosom, better that it should sting us and we should die than that its chill should slowly steal into our hearts; warm it we never can! I have seen faces of women that were fair to look upon, yet one could see that the icicles were forming round these women's hearts. I knew what freezing image lay on the white breasts beneath the laces!