The questions of philosophy proper are human desires and fears and aspirations - human emotions - taking an intellectual form.

We receive the truths of science by compulsion. Nothing but ignorance is able to resist them.

Let one persuade many, and he becomes confirmed and convinced, and cares for no better evidence.

The very hope of experimental philosophy, its expectation of constructing the sciences into a true philosophy of nature, is basedon induction, or, if you please, the a priori presumption, that physical causation is universal; that the constitution of nature is written in its actual manifestations, and needs only to be deciphered by experimental and inductive research; that it is not a latent invisible writing, to be brought out by the magic of mental anticipation or metaphysical mediation.

A fact is a proposition of which the verification by an appeal to the primary sources of our knowledge or to experience is directand simple. A theory, on the other hand, if true, has all the characteristics of a fact except that its verification is possible only by indirect, remote, and difficult means.

Science asks no questions about the ontological pedigree or a priori character of a theory, but is content to judge it by its performance; and it is thus that a knowledge of nature, having all the certainty which the senses are competent to inspire, has been attained--a knowledge which maintains a strict neutrality toward all philosophical systems and concerns itself not with the genesis or a priori grounds of ideas.

All observers not laboring under hallucinations of the senses are agreed, or can be made to agree, about facts of sensible experience, through evidence toward which the intellect is merely passive, and over which the individual will and character have no control.