A Natural Group is steadily fixed, though not precisely limited; it is — William Whewell

"Form or figure is space limited by boundaries. Space has necessarily three dimensions, length, breadth, depth; and no ethers which cannot be resolved into these."

"A Natural System is one which attempts to make all the divisions natural, the widest as well as the narrowest; and therefore applies no characters peremptorily."

"According to the technical language of old writers, a thing and its qualities are described as subject and attributes; and thus a man’s faculties and acts are attributes of which he is the subject. The mind is the subject in which ideas inhere. Moreover, the man’s faculties and acts are employed upon external objects; and from objects all his sensations arise. Hence the part of a man’s knowledge which belongs to his own mind, is subjective: that which flows in upon him from the world external to him, is objective."

"We cannot observe external things without some degree of Thought; nor can we reflect upon our Thoughts, without being influenced in the course of our reflection by the Things which we have observed."

"We unfold out of the Idea of Space the propositions of geometry, which are plainly truths of the most rigorous necessity and universality. But if the idea of space were merely collected from observation of the external world, it could never enable or entitle us to assert such propositions: it could never authorize us to say that not merely some lines, but all lines, not only have, but must have, those properties which geometry teaches. Geometry in every proposition speaks a language which experience never dares to utter; and indeed of which she but half comprehends the meaning."

"The antithesis of Sense & Ideas is the foundation of the Philosophy of Science. No knowledge can exist without the union, no philosophy without the separation, of these two elements."

"Even if we end terror and even if we eliminate tension, even if we reduce arms and restrict conflict, even if peace were to come to the nations, we would turn from this struggle only to find ourselves on a new battleground as filled with danger and as fraught with difficulty as any ever faced by man. For many of our most urgent problems do not spring from the cold war or even from the ambitions of our adversaries. These are the problems which will persist beyond the cold war. They are the ominous obstacles to mans effort to build a great world society--a place where every man can find a life free from hunger and disease-a life offering the chance to seek spiritual fulfillment unhampered by the degradation of bodily misery."

"We were standing where there was a fine view of the harbor and its long stretches of shore all covered by the great army of the pointed firs, darkly cloaked and standing as if they waited to embark. As we looked far seaward among the outer islands, the trees seemed to march seaward still, going steadily over the heights and down to the waters edge."

"Skepticism, like chastity, should not be relinquished too readily."

"Necessità l ci nduce, e non diletto."

"Gentlemen look on this wonder, Whatever the bids of the bidders they cannot be high enough for it, For it the globe lay preparing quintillions of years without one animal or plant, For it the revolving cycles truly and steadily rolld. In this head the all-baffling brain, In it and below it the makings of heroes. (7)"

"Roaming in thought over the Universe, I saw the little that is Good steadily hastening towards immortality, And the vast all that is calld Evil I saw hastening to merge itself and become lost and dead."