In the winter of 1855, Agassiz, resumed his public lectures, as his salary of fifteen hundred was insufficient to support his family, but when the spring came he found himself exhausted by the extra work. And now his noble wife thought out a plan to aid him. She opened a school in their house, for young ladies. Agassiz's surprise and pleasure knew no bounds when he was informed of the project. He immediately took charge of the classes in physical geography, natural history, and botany, giving a lecture daily on one or other of these subjects. The school, with sixty or seventy girls, was continued for eight years, Agassiz having the coöperation of his brother-in-law, Professor Felton, the noted Greek scholar, and other distinguished men. This school was a blessing in more ways than one. All these years, the debts incurred by the publication of the "Fossil Fishes," and the glacial investigations, had burdened him. The wonder was that the genial, untiring worker could labor at all under this depressing load. Noble devotees to science! What have they not suffered to advance the cause of knowledge! We sit by our pleasant firesides and read what others have wrought for us, perhaps in want and sorrow of soul, and we forget to be grateful or to help lift burdens. This school opened by the helpful wife made Agassiz a free man--no longer shackled by that worst form of slavery, debt. Well said John Ruskin: "My first word to all men and boys who care to hear me is, don't get into debt. Starve and go to heaven, but don't borrow.... Don't buy things you can't pay for!" Indefatigable, versatile, comprehensive in mind, Agassiz at once planned another great work, to be published in ten volumes, though it was finally reduced to four: "Contributions to the Natural History of the United States." Mr. Francis C. Gray of Boston, a personal friend and a lover of letters and science, set the subscription before the public. Very soon, to Agassiz's great delight, he received the names of seventeen hundred subscribers, at twelve dollars a volume. He had now reached his fiftieth birthday, completing his first volume of the new work on that day. His students serenaded him, and Longfellow wrote, to be read at the "Saturday Club," composed of Hawthorne, Holmes, Lowell, Dana, and others, this exquisite poem:-- It was fifty years ago, In the pleasant month of May, In the beautiful Pays de Vaud, A child in its cradle lay. And Nature, the old nurse, took The child upon her knee, Saying: "Here is a story-book Thy Father has written for thee." "Come wander with me," she said, "Into regions yet untrod, And read what is still unread In the manuscripts of God." And he wandered away and away With Nature, the dear old nurse, Who sang to him night and day The rhymes of the universe. And whenever the way seemed long, Or his heart began to fail, She would sing a more wonderful song, Or tell a more marvellous tale.