INTRODUCTION þihui

of Fracastorius in 1555. It is divided into fourteen sections,
and gives a historical aecount of the theories on this subject
from Thales down to his own time, the reports of contempo—
raneous explorers, and finally, his own theory, which is based on
the position of the Nile regions in relation to the sun.

The Letters

His Letters, especially those addressed to Rannusio, are the
most useful source, apart from Homocentrica, for the scientific
interests, other than medical, of Fracastorius. 'They were not
consulted by Mencke, who regrets that he was unable to obtain
them; this is the chief defect of his Biography. Humboldt,
who had read Fracastorius with care, in his Kosmos (1844)
twice refers with respect to his acute geological observations.

Geology

In the first passage (p. 379 of ed 1869), he says that, in 1517,
Fraeastorius investigated certain rock strata that had been
uncovered on Monte Bolea near Verona, revealing numerous
marine fossils, and did not fail to recognise '"das Dasein einer
untergangenen oceanischen 'Thierwelt in ihren hinterlassenen
Spuren'; again, p. 910, he says that Fracastorius made similar
observations in the quarries near the citadel of San Felice. In
both passages, Humboldt classes him with Leonardo da Vinci
as far in advance of the geological knowledge of his day. For
then such remains were ascribed to Noah'!s Flood or to some
caprice of Nature, whereas he definitely attributed them to
secular changes of elevation in land and water.'

Favorite Authors

His biographers persist in stating that his favorite authors
were Polybius and Plutarch, but I see no evidence of this in

: See Homocentrica I. 12, for his statement of this; and the letter
to T. Saraina, a Veronese lawyer who had asked him to explain the
marine fossils of the neighboring mountains.* Humboldt does not
mention the specilla ocwlaria of Homocentrica as & forerunner of
the telescope, and says that we cannot find any use of a telescope
in the modern sense before 1608. Olschki, Geschichiöe der Neu—
sprachlichen Wissenschafllichen Literatur, Vol. II. p. 43, says that
Fracastorius is the first to mention the telescope, €denn worauf es
ankommt [i. e. the importance of Cardan's camera obscura or the
lenses of Fracastorius] ist nicht das eine oder das andere Instrument,
sondern die Art und Weise, wie es benutzt und der Zweck, wofür
es verwertet wird'.