Still more distinct notions on the causes of the plague were stated to his contemporaries in the 14th century, by Galeazzo di Santa Sofia, a learned man, a native of Padua, who likewise treated plague-patients at Vienna[175], though in what year is undetermined. He distinguishes carefully _pestilence_ from _epidemy_ and _endemy_. The common notion of the two first accords exactly with that of an epidemic constitution, for both consist, according to him, in an unknown change or corruption of the air; with this difference, that _pestilence_ calls forth diseases of different kinds; _epidemy_, on the contrary, always the same disease. As an example of an _epidemy_, he adduces a cough (influenza) which was observed in all climates at the same time, without perceptible cause; but he recognised the approach of a _pestilence_, independently of unusual natural phenomena, by the more frequent occurrence of various kinds of fever, to which the modern physicians would assign a nervous and putrid character. The _endemy_ originates, according to him, only in local telluric changes—in deleterious influences which develop themselves in the earth and in the water, without a corruption of the air. These notions were variously jumbled together in his time, like every thing which human understanding separates by too fine a line of limitation. The estimation of cosmical influences, however, in the _epidemy_ and _pestilence_, is well worthy of commendation; and Santa Sofia, in this respect, not only agrees with the most intelligent persons of the 14th and 15th centuries, but he has also promulgated an opinion which must, even now, serve as a foundation for our scarcely commenced investigations into cosmical influences[176]. _Pestilence_ and _epidemy_, consist not in alterations of the four primary qualities[177], but in a corruption of the air, powerful, though quite immaterial, and not cognoscible by the senses:—(corruptio aëris non substantialis, sed qualitativa) in a disproportion of the imponderables in the atmosphere, as it would be expressed by the moderns[178]. The causes of the _pestilence_ and _epidemy_ are, first of all, astral influences, especially on occasion of planetary conjunctions; then extensive putrefaction of animal and vegetable bodies, and terrestrial corruptions (corruptio in terra); to which also, bad diet and want may contribute. Santa Sofia considers the putrefaction of locusts, that had perished in the sea, and were again thrown up, combined with astral and terrestrial influences, as the cause of the pestilence in the eventful year of the “_Great Mortality_.”