I think this book is meant for somewhat older children, about ten to fifteen years. We are also immediately requiring some books for much younger children, say five to ten years age. Another thing you just see that every and each item and example for discussion is made very clear in continuous context so that it will be easy for their understanding. As you have done this first book it is very good beginning, so you go on writing and improving and make a series of such books and we shall see to their printing.
Letter to Yogesvara, 4 October, 1970