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

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.

If they are, then the only ultimate truths are the particulars of concrete experience, and no postulate or general assumption is inherent in science until its proceedings become systematic, or the truths already reached give direction to further research.

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

The accidental causes of science are only accidents relatively to the intelligence of a man.

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.

And we owe science to the combined energies of individual men of genius, rather than to any tendency to progress inherent in civilization.