The human body was thus of primary importance as a means of comprehending and coming into relations with the external world. But men also sought to make the environment intelligible to them by projecting into it the images gained from the more general aspects of their life. Such phrases as "pig of iron," "monkey wrench," "battering ram," "lifting crane," remind us of a period in which objects were actually shaped so as to enable the mind to accommodate itself more completely to the thought of their vitality. The Greek sailing vessel, for example, was so constructed--with the body of a bird, with cheeks, eyes, and projecting ears--as to make it seem to the navigators of the time as almost alive. And the dolphins, eagles, ravens, and dragons which threatened England from the prows of the invading Danish fleet have had their prototypes in almost every nation that has betaken itself to the sea. Not less suggestive are the more general aspects of the process. Our ancestor called the earth's satellite the "moon," or "measurer," because it served him as a divider of time. The familiar grains of wheat and barley which he harvested became the units of his measures. So the names of his seasons were based on the fall of the leaves, the reappearance of particular stars, or the periodical inundations upon which he depended for his food. The most primitive method in chronology is that which enables man to orient himself in the world of time by associating particular lunations with vicissitudes of weather, with seasonal aspects of vegetation, and with the constantly changing sights and sounds of the animal world. In the calendar of the Crees,[C] for example, we find such designations as "duck-month," "frog-moon," "leaf-moon," "berries-ripe-month," "buffalo-rutting moon," "leaves-entirely-changed," "leaves-in-the-trees," "fish-catching-moon," "moon-that-strikes-the-earth cold," "coldest-moon," "ice-thawing-moon," "eagles-seen-moon." So in the calendars of Central America and Mexico,[D] the months are named variously after the arrival of birds, the blossoming of flowers, the blowing of winds, the return of mosquitoes, and the appearance of fishes. The Greeks constantly used the movements of birds to mark the seasons; the arrival of the swallow and kite were thus noted. Hesiod tells us how the cry of the crane signaled the departure of winter, while the setting of the Pleiades gave notice to the plowman when to begin his work. The Incas[E] called Venus "the hairy," on account of the brightness of her rays, just as the Peruvians named her the "eight-hour torch," or "the twilight lamp," from the time of her shining. One at least of the three portions into which the Greeks divided their night received its name--[Greek: peri lychnôn haphas]--from the social custom of lighting the lamps at dusk. For whole races the departure of the sun made night a time of danger, and man did his best to lessen the mystery of the heavens by filling their