Eighthly, none of our sense-perceptions is opposed to the acceptance of infinity, since we cannot deny infinity merely because we do not sensibly perceive it; but since sense in itself is included in infinity, and since reason doth confirm infinity, therefore needs must that we posit infinity. Moreover, if we consider well, sense doth present to us an infinite universe. For we perceive an endless series of objects, each one contained by another, nor do we ever perceive either with our external or our internal sense, an object which is not contained by another or similar object.

Lastly before our eyes one thing is seen to bound another; air is as a well between the hills, and mountains between tracts of air, land bounds the sea and again sea bounds all lands; yet in truth there is nothing outside to limit the universe ... so far on every side spreads out huge room for things, free from limit in all directions everywhere. [6]

From the testimony of our sight then we should rather infer the infinite, since there is no object which doth not terminate in another, nor can we experience aught which terminateth in itself.

Common sense tells us that the things of the earth exist only a little, and that true reality is only in dreams.

A glimpse heavenward at a constellation or even at a single star only suggests infinity; actually our vision is limited. We cannot perceive unlimited space; it is immeasurable. The universe, as we know it through our visual experience, is limited. It first came into existence with the formation of matter, and will end with the complete dissolution of matter.

Common sense in an uncommon degree is what the world calls wisdom.

Twelfthly, there is no reason or sense-perception which, since we accept an infinity undivided, utterly simple and all-embracing, will not permit also a corporeal and extended infinity.

Thirteenthly, our own surrounding space which appeareth to us so immense is neither part nor whole in relation to the infinite; nor can it be patient of infinite activity; compared to such activity, indeed, that which can be comprehended by our imbecile minds is merely nonbeing. And to a certain objection it may be replied that we base our argument for infinity not on the dignity of space but on the dignity of the natures [of worlds], since for the same reason that our space doth exist, so also should exist every other possible world; and their power of being is not actuated by our world's being, just as Elpino's power of being is not actuated by the existence of Fracastoro.

It has been said that there is nothing more uncommon than common sense.

The only way to comprehend what mathematicians mean by Infinity is to contemplate the extent of human stupidity.

How much common sense knowledge do we actually have. Imagine that you are a really hard working all your life and you form two new concepts every half-hour... You end up with... a million concepts, because you don't get that old. ...That's not a lot. ...[H]ow many cycles do your neurons have in your life, it's quite limited.

We know by actual observation only a comparatively small part of the whole universe. I will call this "our neighborhood." Even within the confines of this province our knowledge decreases very rapidly as we get away from our own particular position in space and time. It is only within the solar system that our empirical knowledge extends to the second order of small quantities (and that only for g₄₄ and not for the other g_αβ), the first order corresponding to about 10^-8. How the g_αβ outside our neighborhood are, we do not know, and how they are at infinity of space or time we shall never know. Infinity is not a physical but a mathematical concept, introduced to make our equations more symmetrical and elegant. From the physical point of view everything that is outside our neighborhood is pure extrapolation, and we are entirely free to make this extrapolation as we please to suit our philosophical or aesthetical predilections—or prejudices. It is true that some of these prejudices are so deeply rooted that we can hardly avoid believing them to be above any possible suspicion of doubt, but this belief is not founded on any physical basis. One of these convictions, on which extrapolation is naturally based, is that the particular part of the universe where we happen to be, is in no way exceptional or privileged; in other words, that the universe, when considered on a large enough scale, is isotropic and homogeneous.

Common sense is the guy who tells you that you ought to have had your brakes relined last week before you smashed a front end this week. Common sense is the Monday morning quarterback who could have won the ball game if he had been on the team. But he never is. He's high up in the stands with a flask on his hip. Common sense is the little man in a grey suit who never makes a mistake in addition. But it's always someone else's money he's adding up.

Common sense is a phrase employed to denote that degree of intelligence, sagacity, and prudence, which is common to all men.

Philotheo. No corporeal sense can perceive the infinite. None of our senses could be expected to furnish this conclusion; for the infinite cannot be the object of sense-perception; therefore he who demandeth to obtain this knowledge through the senses is like unto one who would desire to see with his eyes both substance and essence. And he who would deny the existence of a thing merely because it cannot be apprehended by the senses, nor is visible, would presently be led to the denial of his own substance and being. Wherefore there must be some measure in the demand for evidence from our sense-perception, for this we can accept only in regard to sensible objects, and even there it is not above all suspicion unless it cometh before the court aided by good judgement. It is the part of the intellect to judge, yielding due weight to factors absent and separated by distance of time and by space intervals. And in this matter our sense-perception doth suffice us and doth yield us adequate testimony, since it is unable to gainsay us; moreover it advertiseth and confesseth his own feebleness and inadequacy by the impression it giveth us of a finite horizon, an impression moreover which is ever changing. Since then we have experience that sense-perception deceiveth us concerning the surface of this globe on which we live, much more should we hold suspect the impression it giveth us of a limit to the starry sphere.

We naturally believe we are more capable of reaching the centre of things than of embracing their circumference, and the visible extent of the world is visibly greater than we. But since we in our turn are greater than small things, we think we are more capable of mastering them, and yet it takes no less capacity to reach nothingness than the whole. In either case it takes an infinite capacity, and it seems to me that anyone who had understood the ultimate principles of things might also succeed in knowing infinity. One depends on the other, and one leads to the other. These extremes touch and join by going in opposite directions, and they meet in God and God alone.

We Are All Infinite