nt and observation were advocated
as the only way of really increasing knowledge. They all derided mere
book-learning. The conception of the world of sense as the original
MS. of which systems of philosophy are but copies, was a familiar
image with them. So also was Bacon's epigrammatic retort to those
who wish to rest on the wisdom of the ancients, that antiquity is the
youth of the world and that we are the true ancients. "We are older,"
said Giordano Bruno, "and have lived longer than our predecessors."

This last argument, indeed, is much older than the sixteenth century.
It was used by the Doctor Mirabilis of the thirteenth, the Franciscan
Friar, Roger Bacon (1214-1292). "The later men are, the more
enlightened they are; and wise men now are ignorant of much the world
will some day know." The truth is that if you are in search of a
Father for Inductive Philosophy, the mediaeval friar has better claims
than his more illustrious namesake. His enthusiasm for the advancement
of learning was not less nobly ambitious and far-reaching, and he
was himself an ardent experimenter and inventor. His _Opus Majus_--an
eloquent outline of his projects for a new learning, addressed in 1265
to Pope Clement IV., through whom he offered to give to the Church the
empire of the world as Aristotle had given it to Alexander--was almost
incredibly bold, comprehensive and sagacious. Fixing upon Authority,
Custom, Popular Opinion, and the Pride of Supposed Knowledge, as the
four causes of human ignorance, he urged a direct critical study of
the Scriptures, and after an acute illustration of the usefulness
of Grammar and Mathematics (widely interpreted), concluded with
Experimental Science as the great source of human knowledge. I have
already quoted (p. 15) the Friar's distinction between the two modes
of Knowing, Argument and Experience, wherein he laid down that it is
only experience that makes us feel certain. It were better, he cried
in his impatience, to burn Aristotle and make a fresh start than to
accept his conclusions without inquiry.

Experimental Science, the sole mistress of Speculative
Science, has three great Prerogatives among other parts
of Knowledge. First, she tests by experiment the noblest
conclusions of all other sciences. Next, she discovers
respecting the notions which other sciences deal with,
magnificent truths to which these sciences can by no means
attain. Her third dignity is that sh