Obviously, this difficulty is much increased when the canvas is widened to include all Europe, and when the aim is to give the reader a just impression of the general tendencies of a whole age, such an age as, for instance, the sixteenth century, over that vast area. If for a History of the World the old plan be adopted--that of telling the story of each nation separately, yet on lines generally similar, cross references and a copious use of chronological tables become helpful, for they enable the contemporaneity of events to be seen at a glance, and as the history of each nation is being written with a view to that of other nations, the tendencies at work in each can be explained and illustrated in a way which shows their parallelism, and gives to the whole that unity of meaning and tendency which a universal history must constantly endeavour to display. The connection between the progress or decline of different peoples is best understood by setting forth the various forms which similar tendencies take in each. To do this is a hard task when the historian is dealing with the ancient world, or with the world outside Europe even in mediæval and post-mediæval times. For the modern European nations it is easier, because, ever since the spread of Christianity made these nations parts of one great ecclesiastical community, similar forces have been at work upon each of them, and every intellectual movement which has told upon one has more or less told upon the others also. [Illustration: THE MASTER-KEY TO THE HIEROGLYPHICS The inscribed stone found at Rosetta, in the Nile delta, in 1799, now preserved in the British Museum. It gave the key to the hieroglyphic writings of Egypt. It is a decree of Ptolemy Epiphanes, promulgated at Memphis in B.C. 196, and as it is inscribed in hieroglyphic and in the script of the country as well as in Greek, it thus solved the long standing mystery of the hieroglyphics of the monuments, which before its discovery had been quite unintelligible. ] [Sidenote: Central Line of Human Development] [Sidenote: The Study of Human Society] [Sidenote: Each Race a Distinct Entity]