When an observation is made on any atomic system that has been prepared in a given way and is thus in a given state, the result will not in general be determinate, i.e. if the experiment is repeated several times under identical conditions several different results may be obtained. If the experiment is repeated a large number of times it will be found that each particular result will be obtained a definite fraction of the total number of times, so that one can say there is a definite probability of its being obtained any time that the experiment is performed. This probability the theory enables one to calculate.

When we make the photon meet a tourmaline crystal, we are subjecting it to an observation. We are observing whether it is polarized parallel or perpendicular to the optic axis. The effect of making the observation is to force the photon entirely into the state of perpendicular polarization. It has to make a sudden jump from being partly in each of these two states to being entirely in one or other of them. Which of the two states it will jump into cannot be predicted, but is governed only by probability laws. If it jumps into the perpendicular state it passes through the crystal and appears on the other side preserving this state of polarization.

Combining this observation with the insight that science has no special method, we arrive at the result that the separation of science and non-science is not only artificial but also detrimental to the advancement of knowledge. If we want to understand nature, if we want to master our physical surroundings, then we must use all ideas, all methods, and not just a small selection of them. The assertion, however, that there is no knowledge outside science - extra scientiam nulla salus - is nothing but another and most convenient fairy-tale.

It may be laid down as a general rule that, if the result of a long series of precise observations approximates a simple relation so closely that the remaining difference is undetectable by observation and may be attributed to the errors to which they are liable, then this relation is probably that of nature.

The present state of the system of nature is evidently a consequence of what it was in the preceding moment, and if we conceive of an intelligence that at a given instant comprehends all the relations of the entities of this universe, it could state the respective position, motions, and general effects of all these entities at any time in the past or future. Physical astronomy, the branch of knowledge that does the greatest honor to the human mind, gives us an idea, albeit imperfect, of what such an intelligence would be. The simplicity of the law by which the celestial bodies move, and the relations of their masses and distances, permit analysis to follow their motions up to a certain point; and in order to determine the state of the system of these great bodies in past or future centuries, it suffices for the mathematician that their position and their velocity be given by observation for any moment in time. Man owes that advantage to the power of the instrument he employs, and to the small number of relations that it embraces in its calculations. But ignorance of the different causes involved in the production of events, as well as their complexity, taken together with the imperfection of analysis, prevents our reaching the same certainty about the vast majority of phenomena. Thus there are things that are uncertain for us, things more or less probable, and we seek to compensate for the impossibility of knowing them by determining their different degrees of likelihood. So it was that we owe to the weakness of the human mind one of the most delicate and ingenious of mathematical theories, the science of chance or probability.

For Posidonius, ouranos, heaven, offers the paradigm for man. The stars teach ethics. The individual who pursues his duties without emotional involvement in them and without the correlative expectation of results, who recognizes honesty as the good and the hallmark of the wise man, and who seeks to honour the higher daimon in himself discovers a fidelity within the soul which is both its overarching oikeiosis and its link to the World-Soul. He sees that the principles of physics can be translated into the laws of psychology from which are derived ethics and the rules of right conduct. Without wavering in his loyalty to the deepest insights of the Stoic tradition, Posidonius exemplified in his own life and thought the ability of the philosopher to penetrate afresh and more precisely the mystery of the kosmos and the less ordered realm in which human beings dwell. His fearlessness of method and the marriage of observation and abstract thought influenced the generations which came immediately after him, and inspired a number of thinkers in the dawn of the European Enlightenment. [paraphrased]

The sciences of observation and experiment are alike in this, that their aim is to detect the constant or recurring features in all events of a certain kind. A meteorologist studies one cyclone in order to compare it with others ; and by studying a number of them he hopes to find out what features in them are constant, that is, to find out what cyclones as such are like. But the historian has no such aim. If you find him on a certain occasion studying the Hundred Years War or the Revolution of 1688, you cannot infer that he is in the preliminary stages of an inquiry whose ultimate aim is to reach conclusions about wars or revolutions as such. If he is in the preliminary stages of any inquiry, it is more likely to be a general study of the Middle Ages or the seventeenth century. This is because the sciences of observation and experiment are organized in one way and history is organized in another. In the organization of meteorology, the ulterior value of what has been observed about one cyclone is conditioned by its relation to what has been observed about other cyclones. In the organization of history, the ulterior value of what is known about the Hundred Years War is conditioned, not by its relation to what is known about other wars, but by its relation to what is known about other things that people did in the Middle Ages.

And the more we realize our own imperfections and limitations, the more we realize, too,that God has a right to be loved above all things by reason of His infinite wisdom and His infinite goodness. Our final observation is this: the supreme truth has Himself spoken to us: He hasrevealed Himself to us, as yet in an obscure manner, but it is the foundation ofour Christian faith. It is in the name of this supreme truth that Jesus speaks,when He says: “In truth, in truth, I say to you.” He is Himself the truth and the life,and by His help from day to day we must gradually live a better life. This far surpasses Plato’s ideal; no longer is it an abstract, philosophic ascent to the supreme truth, but the supreme truth which condescends to reach down to us inorder to raise us up to Himself.

You cannot help being a politician. You cannot live for an hour without being a politician. But what a man generally means when he says that he is not a politician I am afraid is this--that he has been all his life enjoying his political privilege and grossly neglecting his political duties; and in that sense the observation is scarcely to his credit. As a matter of fact, politics, properly understood, is simply Science of Life--the doctrine of the way in which I am to do my duty to my neighbor, which is an essential part of true religion. It is nothing in the world except religion applied to human society; in fact, it is the practical recognition of the Second Table of the Law of God.

The third aspect of my subject is that of science as a method of finding things out. This method is based on the principle that observation is the judge of whether something is so or not. All other aspects and characteristics of science can be understood directly when we understand that observation is the ultimate and final judge of the truth of an idea. But prove used in this way really means test, in the same way that a hundred-proof alcohol is a test of the alcohol, and for people today the idea really should be translated as,

Enter now the theory of quantum mechanics to upend our ideas about the physical nature of the world. Physicists were discovering in their laboratories that the basic properties of atomic particles were being altered just by the simple act of measuring them. Soon after it was discovered that, in certain experimental arrangements, particles at the atomic level do not fully exist prior to being observed. The activity of conscious observation and measurement was actually bringing particles into full existence! This suggests that reality may not be pre-given and "objective," but rather that it is being...

No, the Golden Mean is not a sunny, untroubled nullity, but a deep awareness of possibilities, with one eye cocked toward Comedy and the other eye skewed toward Tragedy, and out of this feat of balanced observation emerges Humor, not as a foolish amusement or an escape from reality, but as a breadth of perception, and what Heracleitus called an attunement of opposite tensions, like that of the bow and the lyre. A reconciliation of opposites, indeed.

It is owing to our limitations that a thing appears to us as single and separate when in truth it is not a separate thing at all.

Let them call it mischief; Then it is past and prosper'd, 'twill be virtue.

There is no part of history so generally useful as that which relates to the progress of the human mind, the gradual improvement of reason, the successive advances of science, the vicissitudes of learning and ignorance, the extinction and resuscitation of arts, and the revolutions of the intellectual world. - If accounts of battles and invasions are peculiarly the business of princes, the useful and elegant arts are not to be neglected, and those who have kingdoms to govern have understandings to cultivate.

This day, much against my will, I did in Drury Lane see two or three houses marked with a red cross upon the doors, and 'Lord have mercy upon us' writ there — which was a sad sight to me, being the first of that kind that to my remembrance I ever saw. It put me into an ill conception of myself and my smell, so that I was forced to buy some roll-tobacco to smell to and chaw — which took away the apprehension.

The world will change for the better when people decide they are sick and tired of being sick and tired of the way the world is, and decide to change themselves.

It has been demonstrated that a species of penicillium produces in culture a very powerful antibacterial substance which affects different bacteria in different degrees. Generally speaking it may be said that the least sensitive bacteria are the Gram-negative bacilli, and the most susceptible are the pyogenic cocci ... In addition to its possible use in the treatment of bacterial infections penicillin is certainly useful... for its power of inhibiting unwanted microbes in bacterial cultures so that penicillin insensitive bacteria can readily be isolated.

What a blessing this smoking is! Perhaps the greatest that we owe to the discovery of America.

I say, Watson,’ he whispered, ‘would you be afraid to sleep in the same room as a lunatic, a man with softening of the brain, an idiot whose mind has lost its grip?’ ‘Not in the least,’ I answered in astonishment. ‘Ah, that’s lucky,’ he said, and not another word would he utter that night.