kinds of things, substances and accidents; and if I prove that the contagion can neither be one nor the other of these I shall have proved that it does not exist; that it is a chimera. Thus, then: substances are either material or spiritual; that the contagion is a spiritual substance, is so absurd an opinion, that no one would presume to advance it; it is, then, useless to speak of it. Material substances are either simple or compound. Now, the contagion is not a simple substance, and I will prove it in three words. It is not an aerial substance, because, if it were, instead of passing from one body to another, it would fly off to its sphere; it is not a watery substance, because it would be dried up by the wind; it is not igneous, because it would burn; it is not earthy, because it would be visible. Moreover, it is not a compound substance, because it would be sensible to the eye, or to the touch; and who has seen it? or touched it? It remains to see if it be an accident. This is still less probable. The doctors say it is communicated from body to body; this is their Achilles; the pretext for so many useless regulations. Now, supposing it an accident, it would be a transferable accident, which is an incongruity. There is not in all philosophy a more evident thing than this, that an accident cannot pass from one subject to another; so if, to avoid this Scylla, they are reduced to call it an accident produced, they avoid Scylla by falling into Charybdis, because if it be produced, it does not communicate itself, it does not propagate, as they declare. These principles allowed, what is the use of talking of botches and carbuncles?"
"It is folly," said one of his hearers.
"No, no," resumed Don Ferrante, "I do not say so. Science is science; we must only know how to employ it. Swellings, purple botches, and black carbuncles, are respectable terms, which have a good and proper signification; but I say they have nothing to do with the question. Who denies that there may be and are such things? We must only prove whence they come."
Here began the vexations of Don Ferrante. So long as he laughed at the contagion, he found respectful and attentive listeners; but when he came to distinguish and demonstrate that the error of the doctors was, not in affirming
