Galilei (1564-1641).[1] Galileo exhibits all the traits characteristic
of modern thinking: the reference from words to things, from memory to
perception and thought, from authority to self-ascertained principles, from
chance opinion, arbitrary opinion, and the traditional doctrines of the
schools, to "knowledge," that is, to one's own, well grounded, indisputable
insight, from the study of human affairs to the study of nature. Study
Aristotle, but do not become his slave; instead of yielding yourselves
captive to his views, use your own eyes; do not believe that the mind
remains unproductive unless it allies itself with the understanding of
another; copy nature, not copies merely! He equals Bacon in his high
estimation of sensuous experience in contrast to the often illusory
conclusions of the reason, and of the value of induction; but he does not
conceal from himself the fact that observation is merely the first step in
the process of cognition, leaving the chief rôle for the understanding.
This, supplementing the defect of experience--the impossibility of
observing all cases--by its _a priori_ concept of law and with its
inferences overstepping the bounds of experience, first makes induction
possible, brings the facts established into connection (their combination
under laws is thought, not experience), reduces them to their primary,
simple, unchangeable, and necessary causes by abstraction from contingent
circumstances, regulates perception, corrects sense-illusions, _i. e_.,
the false judgments originating in experience, and decides concerning the
reality or fallaciousness of phenomena. Demonstration based on experience,
a close union of observation and thought, of fact and Idea (law)--these
are the requirements made by Galileo and brilliantly fulfilled in his
discoveries; this, the "inductive speculation," as Dühring terms it, which
derives laws of far-reaching importance from inconspicuous facts; this,
as Galileo himself recognizes, the distinctive gift of the investigator.
Galileo anticipates Descartes in regard to the subjective character of
sense qualities and their reduction to quantitative distinctions,[2] while