This is how the pair came under the common law of partition walls.

One evening in April, Jacques came home worn out with fatigue, fasting since morning, and profoundly sad with one of those vague sadnesses which have no precise cause, and which seize on you anywhere and at all times; a kind of apoplexy of the heart to which poor wretches living alone are especially subject.

Jacques, who felt stifling in his narrow room, opened the window to breathe a little.

The evening was a fine one, and the setting sun displayed its melancholy splendors above the hills of Montmartre.

Jacques remained pensively at his window listening to the winged chorus of spring harmony which added to his sadness.