“If Descartes’ main aspirations are directed towards a “first truth,” it follows necessarily that the sphere of pure possibilities, and with it the sphere of “probability,” is excluded from philosophy. Thus Descartes ignores, for example, both the art of rhetoric and history, as fields in which “the probable,” rather than the truth prevails.”

The Meaning of Education and other Essays and Addresses https://books.google.com/books?id=H9cKAAAAIAAJ (1898) p. 45 as quoted by Robert Édouard Moritz, Memorabilia Mathematica; Or, The Philomath's Quotation-book https://books.google.com/books?id=G0wtAAAAYAAJ (1914)

Section 9 : Ethical Outlook
Founding Address (1876), Life and Destiny (1913)
Context: There may be, and there ought to be, progress in the moral sphere. The moral truths which we have inherited from the past need to be expanded and restated. In times of misfortune we require for our support something of which the truth is beyond all question, in which we can put an implicit trust, " though the heavens should fall." A merely borrowed belief is, at such time, like a rotten plank across a raging torrent. The moment we step upon it, it gives way beneath our feet.

Source: Rhetoric as Philosophy (1980), pp. 31-32
Context: In the second part of the Phaedrus Plato attempts to clarify the nature of “true” rhetoric. … it does not arise from a posterior unity which presupposes the duality of ratio and passio, but illuminates and influences the passions through its original, imaginative characters. Thus philosophy is not a posterior synthesis of pathos and logos but the original unity of the two under the power of the original archai. Plato sees true rhetoric as psychology which can fulfill its truly “moving” function only if it masters original images [eide]. Thus the true philosophy is rhetoric, and the true rhetoric is philosophy, a philosophy which does not need an “external” rhetoric to convince, and a rhetoric that does not need an “external” content of verity.

Conclusion : The Moral of this Examination
A Perplexed Philosopher (1892)
Context: Stepping out of their proper sphere and arrogating to themselves an authority to which they have no claim, professed teachers of spiritual truths long presumed to deny the truths of the natural sciences. But now professed teachers of the natural sciences, stepping in turn out of their proper sphere and arrogating to themselves an authority to which they have no claim, presume to deny spiritual truths. And there are many, who having discarded an authority often perverted by the influence of dominant wrong, have in its place accepted another authority which in its blank materialism affords as efficient a means for stilling conscience and defending selfish greed as any perversion of religious truth.
Mr. Spencer is the foremost representative of this authority. Widely regarded as the scientific philosopher; eulogized by his admirers as the greatest of all philosophers — as the man who has cleared and illuminated the field of philosophy by bringing into it the exact methods of science — he carries to the common mind the weight of the marvelous scientific achievements of our time as applied to the most momentous of problems. The effect is to impress it with a vague belief that modern science has proved the idea of God to be an ignorant superstition and the hope of a future life a vain delusion.

Selected Shorter Writings (Phillipsburg: PRR Publishing, 1970), p. 463

Time and Individuality (1940)

p, 125
On the Sizes and Distances of the Sun and the Moon (c. 250 BC)

Letter 56 (60), to Hugo Boxel (1674) http://oll.libertyfund.org/?option=com_staticxt&staticfile=show.php%3Ftitle=1711&chapter=144218&layout=html&Itemid=27
Source: The Letters
Context: When you say that if I deny, that the operations of seeing, hearing, attending, wishing, &c., can be ascribed to God, or that they exist in him in any eminent fashion, you do not know what sort of God mine is; I suspect that you believe there is no greater perfection than such as can be explained by the aforesaid attributes. I am not astonished; for I believe that, if a triangle could speak, it would say, in like manner, that God is eminently triangular, while a circle would say that the divine nature is eminently circular. Thus each would ascribe to God its own attributes, would assume itself to be like God, and look on everything else as ill-shaped.
The briefness of a letter and want of time do not allow me to enter into my opinion on the divine nature, or the questions you have propounded. Besides, suggesting difficulties is not the same as producing reasons. That we do many things in the world from conjecture is true, but that our redactions are based on conjecture is false. In practical life we are compelled to follow what is most probable; in speculative thought we are compelled to follow truth. A man would perish of hunger and thirst, if he refused to eat or drink, till he had obtained positive proof that food and drink would be good for him. But in philosophic reflection this is not so. On the contrary, we must take care not to admit as true anything, which is only probable. For when one falsity has been let in, infinite others follow.
Again, we cannot infer that because sciences of things divine and human are full of controversies and quarrels, therefore their whole subject-matter is uncertain; for there have been many persons so enamoured of contradiction, as to turn into ridicule geometrical axioms.

Source: Aphorisms and Reflections (1901), p. 241