Under these circumstances it would have been an easy matter to establish an intercalary cycle, but the demand for this is an affair of practical life: astronomy is concerned only with the calculation. The failure to observe this fact has led the discussion astray. The calendar is of course the most conservative of all human things; centuries after the establishment of very accurate calculations of the course of the moon and the introduction of a good intercalary cycle, the Jews adhered to the empirical observation of the new moon, and we know how difficult it is in modern times to introduce any improvement into the calendar. Because in Babylon there was a central government which could arrange the intercalation in proper fashion, the lunisolar year was kept in order, and in practical life there was no necessity to be able to calculate months and days for several years in advance. The empirical intercalation worked well, and there was no need to replace it by an intercalary cycle. The latter is indeed a simplification undertaken on practical grounds, an intercalating rule being substituted for the immediate astronomical observation: astronomy is concerned only with the calculation and with the further refinement of the rule. In so far as I am able to pronounce upon the material Kugler is right: no cyclically regulated intercalation existed before the Persian period; but from this it is in no way possible to arrive at any decision as to the position of the Babylonian astronomy. The regulation of the months by the phases of the stars was a suggestive problem for the astronomers, and it led to the recognition of the periodicity of the phenomena. This is the _prius_, not the desired establishment of an intercalary cycle. A second means of fixing the months in their position in the solar year is afforded by the regulation by the solstices and equinoxes; but since, as will be shown in the following chapter, the observation of these is difficult and is seldom undertaken, a regulation of this nature is correspondingly rare. It can be demonstrated for the Eskimos[934], the Kwakiutl[935], and the Hopi, whose 13 ‘sun-points’ doubtless correspond to the 13 months[936]. Of the Basuto it is said that an attempt is made to determine the time of sowing from the moon, but that the people commonly go wrong in their reckoning, and after much dispute are obliged to fall back upon the climatic conditions and the state of the vegetation as more certain marks for the time of sowing. Intelligent chiefs, however, rectify the calendar (i. e. the moon-months) by the summer solstice, which they call the summer house of the sun[937].