more accurate than a method depending on a reference to the phases of Nature. However it would seem as if this mode of indicating time would require a greater knowledge of the stars, such as only few peoples possess,--as if it would constantly be necessary to observe a fresh star for each of the smaller divisions of time. This is not the case, since, as appears from statements already made, for the purpose of determining the seasons a star may be observed when it is stationed at other positions in the sky than on the horizon, e. g., very conveniently, at its upper culmination, but other positions, expressed by us in so many degrees above the horizon, may also serve. Just as the advance of the day is discerned from the position of the sun, so the advance of the year is recognised by the position of certain stars at sunrise and sunset. Stars and sun alike are the indicators of the dial of the heavens. A determination of this kind, however, is not so accurate as that from the heliacal risings and settings. Hence the latter pass almost exclusively or at least pre-eminently under consideration wherever, as in Greece, a calendar of the natural year is based upon the stars: sometimes however the upper culmination (μεσουράνημα) is also given. Finally the stars can also be observed at other times of night than just before sunrise or after sunset[549]: the Marshall Islanders, for instance, were accustomed to observe the signs of the weather at 4 a. m. With the lack of a means of accurately telling the time such an observation is very uncertain and unpractical, and is therefore seldom found. In order to determine the time of certain important natural phenomena it is therefore sufficient to know and observe a few stars or constellations with accuracy and certainty. The Pleiades are the most important[550]. It has been asked why this particular constellation, consisting as it does of comparatively small and unimportant stars, should have played so great a part, and the answer given is chiefly that its appearance coincides (though this is true of other stars also) with important phases of the vegetation. This is correct, but something else must be added. To create constellations in which terrestrial objects, animals, and men are arbitrarily seen requires no inconsiderable degree of imaginative power. The Pleiades however form themselves into a group without any aid from the imagination, and can without difficulty be recognised as such. It is because they are easy to recognise immediately that the observation of these stars plays so important a part. A similar case is that of the Magellanic Clouds, which, where they are visible, belong to the best known phenomena of the heavens, and we may also compare the dark starless patches which so largely occupy the attention of primitive peoples, although neither of these two phenomena is used in determining time, since neither can be observed at the favourable moment, viz. the twilight.