We have now detailed, at considerable length, the symptoms of the plague as mentioned by authors of great eminence. To give a detail of _all_ that has been said upon this subject would be impossible; neither indeed can it be thought necessary in the present treatise. Whatever may have been omitted or too slightly mentioned in this section, will naturally be considered when we come to treat of the cure. It now therefore only remains to say, whether the approach of a plague may be known by any visible signs, so that people might in some measure prepare themselves for the ensuing calamity. Were we in possession of an accurate and authentic history of the world, this question might be very easily decided; but the uncertainty of ancient records, the mutilated state of those which we do possess, the diversity of opinions among mankind, and the unhappy disposition to _misrepresent_, so common in all ages, render it very difficult to say any thing upon the subject. If the theory hinted at in this section (that plagues arise from some commotion in the electric fluid) can be allowed to have any foundation in nature, then it ought to follow, that the forerunners of pestilence would be some electric phenomena; and, from a perusal of the first and second sections of this work, it will appear that such an opinion is not altogether unfounded.[109] [109] See p. p. 61, 62. The appearance of immense numbers of insects has likewise been accounted a sign of approaching pestilence; but if we suppose their appearance to be a _sign_, we can scarce imagine their putrefaction to have been a _cause_, of pestilence. In the east we are informed by Dr. Russel that the inhabitants of Aleppo account the appearance of insects, and even _eclipses_, as presages of the plague. They suppose also that the stillness of frogs is a sign of pestilence; but the same author informs us that all these signs failed in 1760. Violent earthquakes and famines seem to be more certain signs, though even these are not always to be depended upon; it being evident from historical accounts that pestilence has sometimes preceded, and sometimes followed, earthquake and famine. Mr. Gibbon, however, ascribes to the above-mentioned causes, viz. insects, earthquakes, and even _comets_, the dreadful plague which took place in the reign of Justinian. At least, all these preceded it; but perhaps the _insects_ were only meant to be accounted the cause of the plague. The cause of the _insects_ must remain in obscurity. According to him, “In a damp but stagnating air, this African fever is generated from the putrefaction of animal substances, and especially from the swarms of locusts, not less destructive to mankind in their death than in their lives.”