Considering that we have every reason to believe the records of great floods to relate to events which actually occurred, however imperfectly remembered, it seems not unreasonable to believe that the tradition of great heats had its origin in observed phenomena. As neither ordinary conflagrations nor volcanic outbursts would have suggested traditions of the kind, it would seem not impossible that at certain times our sun may have acquired for a time unusual lustre and heat, causing great and widely spread destruction among all forms of animal and vegetable life. This idea may possibly seem to many, especially at a first view, too wild to be entertained for a moment. Our sun shines, so far as appears to ordinary observation, with steadfast lustre from year to year, and also from age to age. If an occasional hot season suggests for a while to some that the sun has grown hotter, or a cool season that he has grown cooler, the restoration of cool or warmer weather, as the case may be, causes the thought to be quickly cast on one side that a change of either kind has taken place. Again, if we examine the historical records of past ages, we find little to suggest the idea, or even the possibility, that the sun in former times shone with greater splendour or with less than at present. The men of those days were formed like the men of our own day, and could not have supported any much greater degree of heat or of cold than men can support at present. Any sudden accession (or diminution) of solar light and heat, such as we are considering, would certainly have attracted marked attention, and have been recorded for the benefit of future ages. The geologic record, again, does, indeed, suggest variations in the sun's emission of heat as constituting one among the few available explanations of the existence of tropical forms of life in certain strata and of arctic forms in other strata. But even if this explanation be the true one, which is by no means established, such variations must of necessity have been slow, the condition of increased heat continuing for many ages in succession, and the like with the condition of diminished heat. We have no evidence, historical or geological, of the occurrence of any sudden accession of solar heat, followed by a quick return to the normal temperature, unless we find such evidence in the tradition prevalent among Egyptian, Indian, and Chinese cosmogonists, that at certain recurring epochs in the past our earth has undergone destruction and renovation by fire.