re whence, according to Aristotle, are the materials for induction
derived? What is the character of that "anterior knowledge" which is the
basis of the inductive process?

Induction, says Aristotle, is "the progression from singulars to
universals."[699] It is an illation of the universal from the singular
as legitimated by the laws of thought. All knowledge, therefore, begins
with singulars--that is, with individual objects. And inasmuch as all
knowledge begins with "individual objects," and as the individual is
constantly regarded by Aristotle as the "object of sense," it is claimed
that his doctrine is that all knowledge is derived from _sensation_, and
that science and art result to man (_solely_) by means of _experience._
He is thus placed at the head of the empirical school of philosophy, as
Plato is placed at the head of the ideal school.

[Footnote 699: "Post. Analytic," bk. i. ch. xviii.]

This classification, however, is based upon a very superficial
acquaintance with the philosophy of Aristotle as a whole. The practice,
so commonly resorted to, of determining the character of the
Aristotelian philosophy by the light of one or two passages quoted from
his "Metaphysics," is unjust both to Aristotle and to the history of
philosophic thought. We can not expect to attain a correct understanding
of the views of Aristotle concerning the sources and grounds of all
knowledge without some attention to his psychology. A careful study of
his writings will show that the terms "sensation" (aisthesis) and
"experience" (empeira) are employed in a much more comprehensive sense
than is usual in modern philosophic writings.

"Sensation," in its lowest form, is defined by Aristotle as "an
excitation of the soul through the body,"[700] and, in its higher form,
as the excitation of the soul by any object of knowledge. In this latter
form it is used by him as synonymous with "intuition," and embraces all
immediate intuitive perceptions, whether of sense, consciousness, or
reason. "The universe is derived from particulars, therefore we ought to
have a sensible perception (aisthesis) of these; and this is intellect
(nous)."[701] Intelligence proper, the faculty of first principles, is,
in certain respects, a sense, because it is the source of a class of
truths which, like the perceptions of the senses, are immediately
revealed as facts to be received upon their own evidence. It thus
answers to the "sensus communis" of Cicero, and