INTRODUCTION xxxiii

and to recognise its specific charaecter; and to write, the earliest
chapter on the contagion of pulmonary phthisis.' It has
often been observed that he was the first to see the analogy
between the processes of contagion and the fermentation of
wine; he clearly describes the latter process,? but he never uses
the actual word fermentation' in conneection with contagion.

Astrology

A biographer must not try to explain away all the defects of
his subject, but Fracastorius should at least have the credit
when he accepts the views that in his generation are the most
enlightened. He constantly explains the origin of epidemies
as due to the influence of a conjunction of the planets, which
by its profound effects on earth and water may vitiate the
atmosphere; and he mentions the fact that, before the outbreak
of syphilis, astrologers had predicted an epidemic. For this
acceptance of the astrological theory he should not be called
superstitious, and he has been well defended from this reproach
by C. and D. Singer?: ". . .in the first half of the sixteenth cen—
tury the influence of the planets on human affairs was the work—
ing hypothesis of the advocates of Natwralism. It was a view
of Nature that stood in broad opposition to the theocratic teach^
ing of Christianity. 'The theory thus occupied a place among
the naturalistic school somewhat similar to that filled by the
Theory of Evolution in the last third of the nineteenth century'.
At any rate, his treatise De causis criticorum dierum shows that

: Book II. Ch.9; III. Ch.8. That phthisis is contagious, had of
eourse been known for centuries. 'The contagious character of
phthisis, ophthalmia and psora is clearly stated in Aristotle, Pro—
blemata VII. 8. / Moreover it must be remembered that in the 11th
or 12th century in the much quoted poem Regimen Salernitanum,
of the School of Salerno, the three kinds of contagion by direct
contact, at a distance, and by contact with infected articles, are
specified: Adversus variolas (in cases of variolae).

Seu potius morbi contagia tangere vitent
Aegrum aegrique halitus, velamina, lintea, vestes,
Ipseque quae tetigit male pura corpora dextra.

But Fracastorius first defined the kinds of seminaria that convey
infection in these three ways.

^ Book I. 9.

s See Bibliography.