The practical astronomy of the early Greeks consisted of a few observations on the heavenly bodies, the appearances of which were most conspicuously connected with the common occupations of life. The succession of light and darkness, the recurring phases of the moon, and the vicissitude of the seasons, presented three regular periods of time, which, though all equally forced on the attention, were not all marked with equal distinctness by sensible limits. From the first, and down to the age of Solon, the Greeks seem to have measured their months in the natural way, by the interval between one appearance of the new moon and the next. Hence, their months were of unequal duration; yet they might be described in round numbers as consisting of thirty days. It was soon observed that the revolutions of the moon were far from affording an exact measure of the apparent annual revolution of the sun, and that if this were taken to be equal to twelve of the former, the seasons would pass in succession through all the months of the year. This in itself would have been no evil, and would have occasioned no disturbance in the business of life. Seen under the Greek sky, the stars were scarcely less conspicuous objects than the moon itself: some of the most striking groups were early observed and named, and served, by their risings and settings, to regulate the labours of the husbandman and the adventures of the seaman. COMMERCE AND THE ARTS Commerce appears in Homer’s descriptions to be familiar enough to the Greeks of the heroic age, but not to be held in great esteem. Yet in the _Odyssey_ we find the goddess, who assumes the person of a Taphian chief, professing that she is on her way to Temesa with a cargo of iron to be exchanged for copper: and in the _Iliad_, Jason’s son, the prince of Lemnos, appears to carry on an active traffic with the Greeks before Troy. He sends a number of ships freighted with wine, for which the purchasers pay, some in copper, some in iron, some in hides, some in cattle, some in slaves. Of the use of money the poet gives no hint, either in this description or elsewhere. He speaks of the precious metals only as commodities, the value of which was in all cases determined by weight. The _Odyssey_ represents Phœnician traders as regularly frequenting the Greek ports; but as Phœnician slaves are sometimes brought to Greece, so the Phœnicians do not scruple, even where they are received as friendly merchants, to carry away Greek children into slavery.