The third of this kind of principles is : matter neither originates nor perishes; all the changes in the world concern form only ; a postulate which on the recommendation of common sense has spread through all philosophical schools, not because it is to be taken as having been found so, or as having been demonstrated by arguments a priori, but because if we were to admit that matter itself is fleeting and transitory, nothing at all that is stable and lasting would be left any longer to serve for the explication of phenomena according to universal and perpetual laws, and hence nothing at all would be left for the exercise of the intellect.

That which comes after ever conforms to that which has gone before.

Zeal to do all that is in one's power is, in truth, a proof of piety.

My lectures are published and not published; they will be intelligible to those who heard them, and to none beside.

The specialist is one who never makes small mistakes while moving towards the grand fallacy.

Instead of wishing to see more doctors made by women joining what there are, I wish to see as few doctors, either male or female, as possible. For, mark you, the women have made no improvement - they have only tried to be men and they have only succeeded in being third-rate men.

Some years ago, as Your Serene Highness well knows, I discovered in the heavens many things that had not been seen before our own age. The novelty of these things, as well as some consequences which followed from them in contradiction to the physical notions commonly held among academic philosophers, stirred up against me no small number of professors - as if I had placed these things in the sky with my own hands in order to upset nature and overturn the sciences. They seemed to forget that the increase of known truths stimulates the investigation, establishment, and growth of the arts; not their diminution or destruction.

The first philosophers were astronomers. The heavens remind man ... that he is destined not merely to act, but also to contemplate.

The wise through excess of wisdom is made a fool.

The way positive reinforcement is carried out is more important than the amount.

In my education, as in that of everyone, the moral influences, which are so much more important than all others, are also the most complicated, and the most difficult to specify with any approach to completeness.

You see that man can endure toil: Cato, on foot, led an army through African deserts. You see that thirst can be endured: he marched over sun-baked hills, dragging the remains of a beaten army and with no train of supplies, undergoing lack of water and wearing a heavy suit of armour; always the last to drink of the few springs which they chanced to find. You see that honour, and dishonour too, can be despised: for they report that on the very day when Cato was defeated at the elections, he played a game of ball. You see also that man can be free from fear of those above him in rank: for Cato attacked Caesar and Pompey simultaneously, at a time when none dared fall foul of the one without endeavouring to oblige the other. You see that death can be scorned as well as exile: Cato inflicted exile upon himself and finally death, and war all the while.

If there is something more excellent than the truth, then that is God; if not, then truth itself is God.

Never accept compliments or criticism from someone you wouldn't take advice from.

A geometrician has learned to perform the most difficult demonstrations and calculations, as a monkey has learned to take his little hat off and on...

When alterations in technical terms become necessary, it is desirable that the new term should contain in its form some memorial of the old one.

The number 2 thought of by one man cannot be added to the number 2 thought of by another man so as to make up the number 4.

Dialectical logic undoes the abstractions of formal logic and of transcendental philosophy, but it also denies the concreteness of immediate experience. To the extent to which this experience comes to rest with the things as they appear and happen to be, it is a limited and even false experience. It attains its truth if it has freed itself from the deceptive objectivity which conceals the factors behind the facts - that is, if it understands its world as a historical universe, in which the established facts are the work of the historical practice of man.

Man is a tool-using animal...Without tools he is nothing, with tools he is all.

Every tax, however, is to the person who pays it a badge, not of slavery but of liberty. It denotes that he is a subject to government, indeed, but that, as he has some property, he cannot himself be the property of a master.

People is the name of the body, State of the spirit, of that ruling person that has hitherto suppressed me.

If we make a couple of discoveries here and there we need not believe things will go on like this for ever.... Just as we hit water when we dig in the earth, so we discover the incomprehensible sooner or later.

A good prescription is still more profitable than an absolution.

War as the most extreme political means discloses the possibility which underlies every political idea, namely, the distinction of friend and enemy.

Eat not the heart.

Our assent to the hypothesis implies that it is held to be true of all particular instances. That these cases belong to past or to future times, that they have or have not already occurred, makes no difference in the applicability of the rule to them. Because the rule prevails, it includes all cases.

The state is therefore everyone; the rules within the state are laws which safeguard the welfare of all and which must originate from the welfare of all.

The invention and spread of contraceptives is the proximate cause of our changing morals. The old moral code restricted sexual experience to marriage, because copulation could not be effectively separated from parentage, and parentage could be made responsible only through marriage. But to-day the dissociation of sex from reproduction has created a situation unforeseen by our fathers. All the relations of men and women are being changed by this one factor; and the moral code of the future will have to take account of these new facilities which invention has placed at the service of ancient desires.

But by far the greatest obstacle to the progress of science and to the undertaking of new tasks and provinces therein is found in this - that men despair and think things impossible.

I am happy because I want nothing from anyone. I do not care about money. Decorations, titles or distinctions mean nothing to me. I do not crave praise. The only thing that gives me pleasure, apart from my work, my violin, and my sailboat, is the appreciation of my fellow workers.

Scientific writing is abhorrently stylized and places a premium on poor quality.

If you want to deserve Hell, you need only stay in bed. The world is iniquity; if you accept it, you are an accomplice, if you change it you are an executioner.

The world of immediate experience-the world in which we find ourselves living-must be comprehended, transformed, even subverted in order to become that which it really is.

If any philosopher had been asked for a definition of infinity, he might have produced some unintelligible rigmarole, but he would certainly not have been able to give a definition that had any meaning at all.

With regard to politics and the character of princes and great men, I think I am very moderate. My views of things are more conformable to Whig principles; my representation of persons to Tory prejudices. Nothing can so much prove that men commonly regard more persons than things, as to find that I am commonly numbered among the Tories.

Where any work can be done conformably to the reason which is common to gods and men, there we have nothing to fear; for where we are able to get profit by means of the activity which is successful and proceeds according to our constitution, there no harm is to be suspected.

The quality of feeling is the true psychical representative of the first category of the immediate as it is in its immediacy, of the present in its direct positive presentness. Qualities of feeling show myriad-fold variety, far beyond what the psychologists admit. This variety however is in them only insofar as they are compared and gathered into collections. But as they are in their presentness, each is sole and unique; and all the others are absolute nothingness to it - or rather much less than nothingness, for not even a recognition as absent things or as fictions is accorded to them. The first category, then, is Quality of Feeling, or whatever is such as it is positively and regardless of aught else.

The liturgy of emptiness dispels the capitalist economy of the commodity.

It is not enough for a wise man to study nature and truth; he should dare state truth for the benefit of the few who are willing and able to think.

Things are impressed better by active than by passive repetition. ...It pays better to wait and recollect by an effort from within, than to look at the book again.

If exclusive privileges were not granted, and if the financial system would not tend to concentrate wealth, there would be few great fortunes and no quick wealth. When the means of growing rich is divided between a greater number of citizens, wealth will also be more evenly distributed; extreme poverty and extreme wealth would be also rare.

It is unjust to call imaginary the diseases which are, on the contrary, only too real, since they proceed from our mind, the only regulator of our equilibrium and our health.

There is hardly a pioneer's hut which does not contain a few odd volumes of Shakespeare. I remember reading the feudal drama of Henry V for the first time in a log cabin.

The writers against religion, whilst they oppose every system, are wisely careful never to set up any of their own.

It is better, of course, to know useless things than to know nothing.

A man really writes for an audience of about ten persons. Of course if others like it, that is clear gain. But if those ten are satisfied, he is content.

If a person gave your body to any stranger he met on his way, you would certainly be angry. And do you feel no shame in handing over your own mind to be confused and mystified by anyone who happens to verbally attack you?