Theses de pestilentia

to cause putrefaction.

XVIII.
It is, however, either the air, or diet, or something else common.

XIX.
Air, either through the alteration of primary qualities, or through its entire substance.

XX.
By primary qualities: if it becomes hotter, or more humid, or exceeds in either quality for too long.

XXI.
By entire substance: if it contracts putrefaction, or becomes a vehicle for pernicious vapors.

XXII.
These vapors are either death-bearing spirits, bursting forth from charnel pits or fissures in the earth, or other putrid exhalations, whether from stagnant waters, from decaying corpses, or from elsewhere. I think that contagion should also not poorly be referred here, whether it happens through mutual contact of the suffering, through fomites substances capable of absorbing and transmitting contagious matter, or even at a distance.

XXIII.
But for the heaviness of the heavens to bring about such ruin, four things seem to be required: the powers of the agent, the disposition of the patient, the contact of both, and the duration of the agent within the patient.

Diet