XX. The common causes of our experiencing more or less heat, or more or less light from the sun, are the serene or loaded state of the atmosphere; the oblique direction with which the sun’s rays are reflected on us; the position, or situation of places; the length or shortness of the days; the tranquillity or agitation of the winds, and our vicinity to cold or warm places, such as snowy mountains, or warm subterraneous effluvia. But, abstracted from any of these sublunary or inferior causes, I say, that in the sun itself, is contained a cause, that occasions it to reflect more or less light or heat, and that it actually does reflect more or less light and heat, at some times than it does at others, and that this is in virtue of its own proper nature and disposition. XXI. The reason of which phenomenon is, the transitory spots, which the astronomers have for some time past observed in the sun. These are a sort of darkish places, unequal in size and duration, which seem as if they were on the superficies of the star, and which at different times are more or less numerous, although it has happened, that for years together none of them have appeared. Some believe that the antient Chaldeans had some knowledge of them, for in the Book of Job, we read the following expression of Job’s friend Eliphaz to him, that the Heavens themselves are not exempt from their spots: _Cæli non sunt mundi in conspectu ejus._ On the other hand, the want of telescopes among the ancients, did not render their making observations on these things impossible; for some of these spots are so large, as to be visible without a telescope; as for example that was, which was seen in the year 1706, whose superficies according to the computation of the astronomers, was thirty-six times larger than the whole earth; and when they arrive at this magnitude, or if they are even much less, they may be discerned, by looking at the sun with a glass tinged with any dark colour.