ed by his reiterated and successful attacks, that he was
assailed, during the rest of his life, with a degree of rancour which
seldom originates in a mere difference of opinion. Forgetting that all
knowledge is progressive, and that the errors of one generation call
forth the comments, and are replaced by the discoveries, of the next,
Galileo did not anticipate that his own speculations and incompleted
labours might one day provoke unmitigated censure; and he therefore
failed in making allowance for the prejudices and ignorance of his
opponents. He who enjoys the proud lot of taking a position in advance
of his age, need not wonder that his less gifted contemporaries are left
behind. Men are not necessarily obstinate because they cleave to deeply
rooted and venerable errors, nor are they absolutely dull when they are
long in understanding and slow in embracing newly discovered truths.

It was one of the axioms of the Aristotelian mechanics, that the heavier
of two falling bodies would reach the ground sooner than the other, and
that their velocities would be proportional to their weights. Galileo
attacked the arguments by which this opinion was supported; and when he
found his reasoning ineffectual, he appealed to direct experiment. He
maintained, that all bodies would fall through the same height in the
same time, if they were not unequally retarded by the resistance of the
air: and though he performed the experiment with the most satisfactory
results, by letting heavy bodies fall from the leaning tower of Pisa,
yet the Aristotelians, who with their own eyes saw the unequal weights
strike the ground at the same instant, ascribed the effect to some
unknown cause, and preferred the decision of their master to that of
nature herself.

Galileo could not brook this opposition to his discoveries; nor could
the Aristotelians tolerate the rebukes of their young instructor. The
two parties were, consequently, marshalled in hostile array; when,
fortunately for both, an event occurred, which placed them beyond the
reach of danger. Don Giovanni de Medici, a natural son of Cosmo, had
proposed a method of clearing out the harbour of Leghorn. Galileo, whose
opinion was requested, gave such an unfavourable report upon it, that
the disappointed inventor directed against him all the force of his
malice. It was an easy task to concentrate the malignity of his enemies
at Pisa; and so effectually was this accomplished, that Galileo resolve