And when I saw Louis say good-bye to me, raise his hat to a girl of his acquaintance, and walk on with her side by side down the sidewalk, I was made excited and envious.

I, too, wanted to play this game.
"Well, there's only one thing to do," said Louis, "and that is, you must get a girl." Which is more difficult than it sounds.

Let me show you, at the expense of a slight going aside.

Louis did not know girls in their home life.
He had the entree to no girl's home.

And of course, I, a stranger in this new world, was similarly circumstanced.