This book takes its origin in a course of lectures on the history and progress of Astronomy arranged for me in the year 1887 by three of my colleagues (A.C.B., J.M., G.H.R.), one of whom gave the course its name. If I may claim for them any merit, I should say it consists in their simple statement and explanation of scientific facts and laws. The biographical details are compiled from all readily available sources, there is no novelty or originality about them; though it is hoped that there may be some vividness. I have simply tried to present a living figure of each Pioneer in turn, and to trace his influence on the progress of thought.
Heidi (/ˈhaɪdi/; German: [ˈhaɪdi]) is a work of children's fiction published in 1881 by Swiss author Johanna Spyri, originally published in two parts as Heidi: Her Years of Wandering and Learning (German: Heidis Lehr- und Wanderjahre) and Heidi: How She Used What She Learned (German: Heidi kann brauchen, was sie gelernt hat). It is a novel about the events in the life of a young girl in her paternal grandfather's care in the Swiss Alps. It was written as a book "for children and those who love children" (as quoted from its subtitle).Heidi is one of the best-selling books ever written and is among the best-known works of Swiss literature.
At the solicitation of many friends I am publishing, unknown to my daughter, these letters written by her while in the service of the Y.M.C.A. The letters have come to me scribbled in lead pencil and in every color of ink upon an assortment of stationery that in itself revealed the snatching of whatever opportunity to write occurred in a busy life.