They fill it as they would fill the meal-bag, for the sake of the meal and without a thought of the bag.
In fact a boy's mind is more like the boy himself.

It will not do to try to make a man out of him by stuffing meat and bread down his throat.

The meat and bread fill him very quickly, but he isn't fully-grown when he is full.

To make a man of him we must give him food in proper quantities, and let it help him to grow, and the things you learn in school are chiefly valuable as food for the mind.
Education makes the intellect grow as truly as food makes the body do so; and so I say that Sam Hardwicke's superiority in intellect to the boys and even to most of the men about him, consisted of something more than merely a larger stock of information.

He was intellectually larger than they, and if any boy who reads this book supposes that a well-trained intellect is of no account in the practical affairs of life, it is time for him to begin correcting some very dangerous notions.
To get back to the story, I must stop moralizing and say that when Sam made up his mind to volunteer, a number of boys in the neighborhood determined to follow his example, and, as Sam has already explained, the little company was organized, under Sam's command as captain.