Science! true daughter of Old Time thou art!
alterest all things with thy peering eyes.
preyest thou thus upon the poet's heart,
Vulture, whose wings are dull realities?
How should he love thee? or how deem thee wise,
Who wouldst not leave him in his wandering.
To seek for treasure in the jewelled skies,
Albeit he soared with an undaunted wing?
Hast thou not dragged Diana from her car?
And driven the Hamadryad from the wood
To seek a shelter in some happier star?
Hast thou not torn the Naiad from her flood,
The Elfin from the green grass, and from me
The summer dread beneath the tamarind tree?
Almost every major systematic error which has deluded men for thousands of years relied on practical experience. Horoscopes, incantations, oracles, magic, witchcraft, the cures of witch doctors and of medical practitioners before the advent of modern medicine, were all firmly established through the centuries in the eyes of the public by their supposed practical successes. The scientific method was devised precisely for the purpose of elucidating the nature of things under more carefully controlled conditions and by more rigorous criteria than are present in the situations created by practical problems.
We find it hard to picture to ourselves the state of mind of a man of older days who firmly believed that the Earth was the centre of the Universe, and that all the heavenly bodies revolved around it. He could feel beneath his feet the writhings of the damned amid the flames; very likely he had seen with his own eyes and smelt with his own nostrils the sulphurous fumes of Hell escaping from some fissure in the rocks. Looking upwards, he beheld ... the incorruptible firmament, wherein the stars hung like so many lamps.
A visitor to Niels Bohr's country cottage, noticing a horseshoe hanging on the wall, teasing the eminent scientist about this ancient superstition. 'Can it be true that you, of all people, believe it will bring you luck?'
'Of course not,' replied Bohr, 'but I understand it brings you luck whether you believe it or not.'
Here's a riddle for the kids. A man leaves his house for a walk. He walks a mile due south, a mile due east, and a mile due north, and finds he is back where he started. What is the man's name?
Yes, Virginia, his name is Santa Claus. And his house is at the North Pole.
But don't go looking for him there, Virginia. Here's the cold fact: Santa Claus doesn't live at the North Pole.
I knew from a young age that there was something fishy about Santa's address. At the age of five or six I discovered that the North Pole is in the middle of the Arctic Ocean. I asked my mother about this and she said that the ocean is frozen. Santa's workshop, she said, is built on the ice.
It sounded reasonable, and a little research in the geography book confirmed her story. The Arctic Ocean is indeed mostly frozen, and the ice at the North Pole is typically ten feet thick (or so said the book at the time). Thick enough to support a workshop and an army of elves.
But, alas, Virginia, it's not that simple. For one thing, the sea ice is drifting all the time, in a direction away from Siberia toward Greenland. Soviet and American scientists sometimes set up research stations on the thicker parts of the ice and go with the flow. A station might drift a thousand miles or more during its lifetime.
If Santa built his workshop on the ice at the North Pole, it wouldn't stay there. It would drift away. Next thing you know, elves, toys, reindeers and sleigh would be floating into the North Atlantic on a rapidly melting ice island.
What's that you say, Virginia? Maybe Santa's workshop is built on the floor of the sea, right smack at the North Pole? An underwater factory that Santa enters and exits by submarine?
Hmmm, a clever idea. But even that doesn't quite work. It turns out that the floor of the Arctic Ocean has a tricky way of moving around with respect to the pole.
The geographical North Pole is defined as the place where the Earth's spin axis intersects the crust. But the body of the Earth wobbles with respect to the rotation axis, something an astronomer named Chandler discovered back in 1891. No one is quite sure what causes the Chandler wobble -- probably a shift of mass in the body of the Earth, or in the oceans, or in the atmosphere. The Earth wobbles like the wheel of a car when a tire gets out of balance.
I'll grant you it's not much of a wobble, Virginia. The Earth's crust wobbles about the pole in a circle about 50 feet in diameter every 14 months. Still, if Santa had a workshop on the floor of the sea, it would wobble too.
And we won't even talk about plate tectonics.
So you see, Virginia, with all this drifting and slipping it's simply not practical for Santa Claus to locate his workshop at the geographic North Pole. Not unless he wants to mount his entire operation on a giant sleigh and continually go moving about on the ice.
And now! With global warming!
But not to worry. There is no need for Santa to take up residence at an unsteady, rapidly warming pole. He has found a firmer address.
The real North Pole, Virginia, is in your heart.
Study science with earnestness -- search into nature -- elicit the truth -- reason on it, and reject all which will not stand the closest investigation. Keep your imagination within bounds, taking heed lest it run away with your judgment. Above all, let me warn you young ones of the danger of being led away by the superstitions which at this day of boasted progress are a disgrace to the age, and which afford astonishing proofs of the vast floods of ignorance overwhelming and desolating the highest places.
There is another approach to the extraterrestrial hypothesis of UFO origins. This assessment depends on a large number of factors about which we know little, and a few about which we know literally nothing. I want to make some crude numerical estimate of the probability that we are frequently visited by extraterrestrial beings.
Now, there is a range of hypotheses that can be examined in such a way. Let me give a simple example: Consider the Santa Claus hypothesis, which maintains that, in a period of eight hours or so on December 24-25 of each year, an out-sized elf visits one hundred million homes in the United States. This is an interesting and widely discussed hypothesis. Some strong emotions ride on it, and it is argued that at least it does no harm.
We can do some calculations. Suppose that the elf in question spends one second per house. This isn't quite the usual picture – "Ho, Ho, Ho," and so on – but imagine that he is terribly efficient and very speedy; that would explain why nobody ever sees him very much – only one second per house, after all. With a hundred million houses he has to spend three years just filling stockings. I have assumed he spends no time at all in going from house to house. Even with relativistic reindeer, the time spent in a hundred million houses is three years and not eight hours. This is an example of hypothesis-testing independent of reindeer propulsion mechanisms or debates on the origins of elves. We examine the hypothesis itself, making very straightforward assumptions, and derive a result inconsistent with the hypothesis by many orders of magnitude. We would then suggest that the hypothesis is untenable.
I have from my childhood, in conformity with the precepts of a mother void of all imaginary fear, been in the constant habit of taking toads in my hand, and applying them to my nose and face as it may happen. My motive for doing this very frequently is to inculcate the opinion I have held, since I was told by my mother, that the toad is actually a harmless animal; and to whose manner of life man is certainly under some obligation as its food is chiefly those insects which devour his crops and annoy him in various ways.
In those parts of the world where learning and science has prevailed, miracles have ceased; but in those parts of it as are barbarous and ignorant, miracles are still in vogue.
As soon as your reasoning, sprung from that godlike mind, lifts up its voice to proclaim the nature of the universe, then the terrors of the mind take flight, the ramparts of the world roll apart, and I see the march of events throughout the whole of space. The majesty of the gods  is revealed and those quiet habitations, never shaken by storms or drenched by rain-clouds or defaced by white drifts of snow which a harsh frost congeals. A cloudless ether roofs them and laughs with radiance lavishly diffused. All their wants are supplied by nature, and nothing at any time cankers their peace of mind. But nowhere do I see the halls of Acheron,  though the earth is no barrier to my beholding all that passes underfoot in the space beneath. At this I am seized with a divine delight and a shuddering awe that by your power nature stands thus unveiled and made manifest in every part.
As children in blank darkness tremble and start at everything, so we in broad daylight are oppressed at times by fears as baseless as those horrors which children imagine coming upon them in the dark. This dread and darkness of the mind cannot be dispelled by the sunbeams, the shining shafts of day, but only by an understanding of the outward form and inner workings of nature.