ized the infinity
of research and the awful brevity of time. His reflections on old age give
proof enough of this. If he missed the labour in the full harvest-field,
the glimpse of the distant mountain tops, suffused for the first time by
the new light, he missed likewise the wearing labour which fell upon the
shoulders of those who were compelled by the new philosophy to use new
methods in presenting to the world the results of their midnight research.
Such work as Cardan undertook in the composition of his moral essays, and
in the Commentary on Hippocrates put no heavy tax on the brain or the
vital energies; the Commentary was of portentous length, but it was not
much more than a paraphrase with his own experiences added thereto.
Mathematics were his pastime, to judge by the ease and rapidity with which
he solved the problems sent to him by Francesco Sambo of Ravenna and
others.[296] He worked hard no doubt, but as a rule mere labour inflicts
no heavier penalty than healthy fatigue. The destroyer of vital power and
spring is hard work, combined with that unsleeping diligence which must be
exercised when a man sets himself to undertake something more complex than
the mere accumulation of data, when he is forced to keep his mental powers
on the strain through long hours of selection and co-ordination, and to
fix and concentrate his energies upon the task of compelling into symmetry
the heap of materials lying under his hand. The _De Subtilitate_ and the
_De Varietate_ are standing proofs that Cardan did not overstrain his
powers by exertion of this kind.

Leaving out of the reckoning his mathematical treatises, the vogue enjoyed
by Cardan's published works must have been a short one. They came to the
birth only to be buried in the yawning graves which lie open in every
library. At the time when Spon brought out his great edition in ten folio
volumes in 1663, the mists of oblivion must have been gathering around the
author's fame, and in a brief space his words ceased to have any weight in
the teaching of that Art he had cultivated with so great zeal and
affection. The mathematician who talked about "Cardan's rule" to his
pupils was most likely ignorant both of his century and his birthplace.
Had it not been for the references made by writers like Burton to his
dabblings in occult learning, his claims to read the stars, and to the
guidance of a peculiar spirit, his name would have been now unknown, save
to a few algebrais