No epidemic ever prevailed during which the need of more accurate information was not felt, and during which the wish of the learned was not loudly expressed, to become acquainted with the secret springs of such stupendous engines of destruction. Was the disease of a new character?—the spirit of inquiry was roused among physicians; nor were the most eminent of them ever deficient either in courage or in zeal for investigation. When the glandular plague first made its appearance as an universal epidemic, whilst the more pusillanimous, haunted by visionary fears, shut themselves up in their closets, some physicians at Constantinople, astonished at the phenomenon, opened the boils of the deceased. The like has occurred both in ancient and modern times, not without favourable results for science; nay, more matured views excited an eager desire to become acquainted with similar or still greater visitations among the ancients; but as later ages have always been fond of referring to Grecian antiquity, the learned of those times, from a partial and meagre predilection, were contented with the descriptions of Thucydides, even where nature had revealed, in infinite diversity, the workings of her powers. These researches, if indeed they deserved that name, were never scientific or comprehensive. They never seized but upon a part, and no sooner had the mortality ceased, than the scarcely awakened zeal relapsed into its former indifference to the interesting phenomena of nature, in the same way as abstemiousness, which had ever been practised during epidemics, only as a constrained virtue, gave place, as soon as the danger was over, to unbridled indulgence. This inconstancy might almost bring to our mind the pious Byzantines who, on the shock of an earthquake, in 529, which appeared as the prognostic of the great epidemic, prostrated themselves before their altars by thousands, and sought to excel each other in Christian self-denial and benevolence; but no sooner did they feel the ground firm beneath their feet, than they again abandoned themselves, without remorse, to all the vices of the metropolis. May I be pardoned for this comparison of scientific zeal with other human excitements? Alas! even this is a virtue which few practise for its own sake, and which, with the multitude, stands quite as much in need as any other, of the incentives of fear and reward.