“Does one error disappear only to make room for another?” … [L]et us look at the science of astronomy. How grand and magnificent have been the discoveries in that field of knowledge. What victories over error have been achieved by the telescope. That instrument did … bring down and dispel vast clouds of error, both in respect of the sky and of our planet. It must be confessed, too, that it took something from the importance of our planet. The idea that all the hosts of heaven are mere appendages to this earth is no longer entertained by average men, and … [almost no men] now stand by the old theory for which the church proposed to murder Galileo. Men are compelled to admit that the Genesis by Moses is less trustworthy as to the time of creating the heavens and the earth than are the rocks and the stars.

[Modern science] passed through a long period of uncertainty and inconclusive experiment, but as the instrumental aids to research improved, and the results of observation accumulated, phantoms of the imagination were exorcised, idols of the cave were shattered, trustworthy materials were obtained for logical treatment, and hypotheses by long and careful trial were converted into theories.

[Relativist] Rel. There is a well-known proposition of Euclid which states that “Any two sides of a triangle are together greater than the third side.” Can either of you tell me whether nowadays there is good reason to believe that this proposition is true?
[Pure Mathematician] Math. For my part, I am quite unable to say whether the proposition is true or not. I can deduce it by trustworthy reasoning from certain other propositions or axioms, which are supposed to be still more elementary. If these axioms are true, the proposition is true; if the axioms are not true, the proposition is not true universally. Whether the axioms are true or not I cannot say, and it is outside my province to consider.

For the most part we humans live with the false impression of security and a feeling of being at home in a seemingly trustworthy physical and human environment. But when the expected course of everyday life is interrupted, we are like shipwrecked people on a miserable plank in the open sea, having forgotten where they came from and not knowing whither they are drifting. But once we fully accept this, life becomes easier and there is no longer any disappointment.

I will give you a “celestial multiplication table.” We start with a star as the unit most familiar to us, a globe comparable to the sun. Then—
A hundred thousand million Stars make one Galaxy;
A hundred thousand million Galaxies make one Universe.
The figures may not be very trustworthy, but I think they give a correct impression.

If logical training is to consist, not in repeating barbarous scholastic formulas or mechanically tacking together empty majors and minors, but in acquiring dexterity in the use of trustworthy methods of advancing from the known to the unknown, then mathematical investigation must ever remain one of its most indispensable instruments. Once inured to the habit of accurately imagining abstract relations, recognizing the true value of symbolic conceptions, and familiarized with a fixed standard of proof, the mind is equipped for the consideration of quite other objects than lines and angles. The twin treatises of Adam Smith on social science, wherein, by deducing all human phenomena first from the unchecked action of selfishness and then from the unchecked action of sympathy, he arrives at mutually-limiting conclusions of transcendent practical importance, furnish for all time a brilliant illustration of the value of mathematical methods and mathematical discipline.

In my opinion, there is absolutely no trustworthy proof that talents have been improved by their exercise through the course of a long series of generations. The Bach family shows that musical talent, and the Bernoulli family that mathematical power, can be transmitted from generation to generation, but this teaches us nothing as to the origin of such talents. In both families the high-watermark of talent lies, not at the end of the series of generations, as it should do if the results of practice are transmitted, but in the middle. Again, talents frequently appear in some member of a family which has not been previously distinguished.

My books have sold largely in England, have been translated into many languages, and passed through several editions in foreign countries. I have heard it said that the success of a work abroad is the best test of its enduring value. I doubt whether this is at all trustworthy; but judged by this standard my name ought to last for a few years.

My third teacher was by far the wisest and most trustworthy, though he used neither books nor pictures, and was a poor lecturer. He was painfully silent, would talk only after repeated urging, and then often spoke almost unintelligibly in a language which had to be translated to be understood. But what he had to say was final and exhaustive, and could be passed on in good conscience to those who either would not or could not go directly to him for information. This teacher was Nature itself.

No excavation ought to ever be permitted except under the immediate eye of a responsible and trustworthy superintendent. ... Superfluous precision may be regarded as a fault on the right side. ... [P]ottery [i]s the human fossil, so widely is it distributed.
Some of the basic principals of digging he adopted.

Our most trustworthy safeguard in making general statements on this question is imagination. If we can imagine the breaking of a law of physics then… it is in some degree an empirical law. With a purely rational law we could not conceive an alternative… This ultimate criterion serves as an anchor to keep us from drifting unduly in a perilous sea of thought.

The absorption of oxygen and the elimination of carbon dioxide in the lungs take place by diffusion alone. There is no trustworthy evidence of any regulation of this process on the part of the organism.

These days at ten o’clock at night a most alarming wonder has manifested itself in the skies. The firmament was rent asunder and through this gap one could distinguish chariots and armies, riders with yellow, white, red and black standards, though to do battle against each other. This awesome and unusual vision continued from ten at night till about two of the morning, and was witnessed with alarm and dismay by many honest and trustworthy people. The significance thereof is known but to God Almighty, Who may graciously prevent the shedding of innocent blood.

With me the horrid doubt always arises whether the convictions of man’s mind, which has been developed from the mind of the lower animals, are of any value or at all trustworthy. Would any one trust in the convictions of a monkey’s mind, if there are any convictions in such a mind.