Of sources which are not in the form of writing, the most important are: (1) implements of warfare, agriculture, household economy, and the chase, large quantities of which have been brought to light in various parts of the world, and which bear witness to the manner of life prevailing among the peoples who produced and used them; (2) coins, hoarded up in treasuries or buried in tombs or ruins of one sort or another, frequently preserving likenesses of important sovereigns, with dates and other materials of use especially in fixing chronology; (3) works of art, surviving intact or with losses or changes inflicted by the ravages of weather and human abuse--the tombs of the Egyptians, the sculpture of the Greeks, the architecture of the Middle Ages, or the paintings of the Renaissance; (4) other constructions of a more practical character, particularly dwelling-houses, roads, bridges, aqueducts, walls, gates, fortresses, and ships,--some well preserved and surviving as they were first fashioned, others in ruins, and still others built over and more or less obscured by modern improvement or adaptation. [Sidenote: Various ways of using sources] These are some of the things to which the writer of history must go for his facts and for his inspiration, and it is to these that the student, whose business is to learn and not to write, ought occasionally to resort to enliven and supplement what he finds in the books. As there are many kinds of sources, so there are many ways in which such materials may be utilized. If, for example, you are studying the life of the Greeks and in that connection pay a visit to a museum of fine arts and scrutinize Greek statuary, Greek vases, and Greek coins, you are very clearly using sources. If your subject is the church life of the later Middle Ages and you journey to Rheims or Amiens or Paris to contemplate the splendid cathedrals in these cities, with their spires and arches and ornamentation, you are, in every proper sense, using sources. You are doing the same thing if you make an observation trip to the Egyptian pyramids, or to the excavated Roman forum, or if you traverse the line of old Watling Street--nay, if you but visit Faneuil Hall, or tramp over the battlefield of Gettysburg. Many of these more purely "material" sources can be made use of only after long and sometimes arduous journeys, or through the valuable, but somewhat less satisfactory, medium of pictures and descriptions. Happily, however, the art of printing and the practice of accumulating enormous libraries have made possible the indefinite duplication of _written_ sources, and consequently the use of them at almost any time and in almost any place. There is but one Sphinx, one Parthenon, one Sistine Chapel; there are not many Roman roads, feudal castles, or Gothic cathedrals; but scarcely a library in any civilized country is without a considerable number of the monumental _documents_