urst upon him like a revelation, and after mastering Euclid he
turned to Archimedes with equal enthusiasm. Mathematics now absorbed his
mind, and the father was obliged to yield to the bent of his genius,
which seemed to disdain the regular professions by which social position
was most surely effected. He wrote about this time an essay on the
Hydrostatic Balance, which introduced him to Guido Ubaldo, a famous
mathematician, who induced him to investigate the subject of the centre
of gravity in solid bodies. His treatise on this subject secured an
introduction to the Grand Duke of Tuscany, who perceived his merits, and
by whom he was appointed a lecturer on mathematics at Pisa, but on the
small salary of sixty crowns a year.

This was in 1589, when he was twenty-five, an enthusiastic young man,
full of hope and animal spirits, the charm of every circle for his
intelligence, vivacity, and wit; but bold and sarcastic, contemptuous of
ancient dogmas, defiant of authority, and therefore no favorite with
Jesuit priests and Dominican professors. It is said that he was a
handsome man, with bright golden locks, such as painters in that age
loved to perpetuate upon the canvas; hilarious and cheerful, fond of
good cheer, yet a close student, obnoxious only to learned dunces and
narrow pedants and treadmill professors and bigoted priests,--all of
whom sought to molest him, yet to whom he was either indifferent or
sarcastic, holding them and their formulas up to ridicule. He now
directed his inquiries to the mechanical doctrines of Aristotle, to
whose authority the schools had long bowed down, and whom he too
regarded as one of the great intellectual giants of the world, yet not
to be credited without sufficient reasons. Before the "Novum Organum"
was written, he sought, as Bacon himself pointed out, the way to arrive
at truth,--a foundation to stand upon, a principle tested by experience,
which, when established by experiment, would serve for sure deductions.

Now one of the principles assumed by Aristotle, and which had never been
disputed, was, that if different weights of the same material were let
fall from the same height, the heavier would reach the ground sooner
than the lighter, and in proportion to the difference of weight. This
assumption Galileo denied, and asserted that, with the exception of a
small different owing to the resistance of the air, both would fall to
the ground in the same space of time. To prove his posit