ns of
nature, have darkened the plainest appearances, and bewildered mankind
in errour and obscurity.

Boerhaave had now for nine years read physical lectures, but without
the title or dignity of a professor, when, by the death of professor
Hotten, the professorship of physick and botany fell to him of course.

On this occasion he asserted the simplicity and facility of the
science of physick, in opposition to those that think obscurity
contributes to the dignity of learning, and that to be admired it is
necessary not to be understood.

His profession of botany made it part of his duty to superintend the
physical garden, which improved so much by the immense number of new
plants which he procured, that it was enlarged to twice its original
extent.

In 1714, he was deservedly advanced to the highest dignities of the
university, and, in the same year, made physician of St. Augustin's
hospital in Leyden, into which the students are admitted twice a week,
to learn the practice of physick.

This was of equal advantage to the sick and to the students, for the
success of his practice was the best demonstration of the soundness of
his principles.

When he laid down his office of governour of the university, in 1715,
he made an oration upon the subject of "attaining to certainty in
natural philosophy;" in which he declares, in the strongest terms, in
favour of experimental knowledge; and reflects, with just severity,
upon those arrogant philosophers, who are too easily disgusted with
the slow methods of obtaining true notions by frequent experiments;
and who, possessed with too high an opinion of their own abilities,
rather choose to consult their own imaginations, than inquire into
nature, and are better pleased with the charming amusement of forming
hypotheses, than the toilsome drudgery of making observations.

The emptiness and uncertainty of all those systems, whether venerable
for their antiquity, or agreeable for their novelty, he has evidently
shown; and not only declared, but proved, that we are entirely
ignorant of the principles of things, and that all the knowledge we
have, is of such qualities alone as are discoverable by experience, or
such as may be deduced from them by mathematical demonstration.

This discourse, filled as it was with piety, and a true sense of the
greatness of the supreme being, and the incomprehensibility of his
works, gave such offence to a professor of Franeker, who professed the
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