public IEnumerator AddWordToBook(string word)
    {
        /* Add the word to a free book */
        foreach (Book book in books)
        {
            if (!book.Used)
            {
                cauldron.SendCloudsToBook(book.transform.position);
                yield return(new WaitForSeconds(0.75f));

                book.SetText(word);
                break;
            }
        }
    }