They say cowardice is infectious; but then argument is, on the other hand, a great emboldener.

The cruelest lies are often told in silence. A man may have sat in a room for hours and not opened his teeth, and yet come out of that room a disloyal friend or a vile calumniator. And how many loves have perished because, from pride, or spite, or diffidence, or that unmanly shame which withholds a man from daring to betray emotion, a lover, at the critical point of the relation, has but hung his head and held his tongue?

An appeal to his alarm is never a good plan to rid oneself of a spirited young man.

So long as we love we serve; so long as we are loved by others, I would almost say that we are indispensable; and no man is useless while he has a friend.

Books are good enough in their own way, but they are a mighty bloodless substitute for life.

Sanity itself is a kind of convention.

All who have meant good work with their whole hearts, have done good work, although they may die before they have the time to sign it. Every heart that has beat strong and cheerfully has left a hopeful impulse behind it in the world, and bettered the tradition of mankind. And even if death catch people, like an open pitfall, and in mid-career, laying out vast projects, and planning monstrous foundations, flushed with hope, and their mouths full of boastful language, they should be at once tripped up and silenced: is there not something brave and spirited in such a termination? and does not life go down with a better grace, foaming in full body over a precipice, than miserably straggling to an end in sandy deltas?

There are circumstances in which even the least energetic of mankind learn to behave with vigour and decision; and the most cautious forget their prudence and embrace foolhardy resolutions.

In anything fit to be called by the name of reading, the process itself should be absorbing and voluptuous; we should gloat over a book, be rapt clean out of ourselves, and rise from the perusal, our mind filled with the busiest, kaleidoscopic dance of images, incapable of sleep or of continuous thought. The words, if the book be eloquent, should run thenceforward in our ears like the noise of breakers, and the story, if it be a story, repeat itself in a thousand coloured pictures to the eye.

Age may have one side, but assuredly Youth has the other. There is nothing more certain than that both are right, except perhaps that both are wrong. Let them agree to differ; for who knows but what agreeing to differ may not be a form of agreement rather than a form of difference?

Sight-seeing is the art of disappointment.

He and his tyrannicide! I am in a mad fury about these explosions. If that is the new world! Damn O'Donovan Rossa; damn him behind and before, above, below, and roundabout; damn, deracinate, and destroy him, root and branch, self and company, world without end. Amen. I write that for sport if you like, but I will pray in earnest, O Lord, if you cannot convert, kindly delete him!

The devil, depend upon it, can sometimes do a very gentlemanly thing.

Them that die will be the lucky ones!

The difficulty of literature is not to write, but to write what you mean; not to affect your reader, but to affect him precisely as you wish.

Time passes quickly with lovers.

Give us grace and strength to forbear and to persevere. Give us courage and gaiety and the quiet mind, spare to us our friends, soften to us our enemies.

Perpetual devotion to what a man calls his business, is only to be sustained by perpetual neglect of many other things.

The imagination loves to trifle with what is not.

It seems as if marriage were the royal road through life, and realised, on the instant, what we have all dreamed on summer Sundays when the bells ring, or at night when we cannot sleep for the desire of living. They think it will sober and change them. Like those who join a brotherhood, they fancy it needs but an act to be out of the coil and clamour for ever. But this is a wile of the devil's. To the end, spring winds will sow disquietude, passing faces leave a regret behind them, and the whole world keep calling and calling in their ears. For marriage is like life in this - that it is a field of battle, and not a bed of roses.

Decisive actions are often taken in a moment and without any conscious deliverance from the rational parts of man.

Fiction is to the grown man what play is to the child; it is there that he changes the atmosphere and tenor of his life.

It is as natural and as right for a young man to be imprudent and exaggerated, to live in swoops and circles, and beat about his cage like any other wild thing newly captured, as it is for old men to turn gray, or mothers to love their offspring, or heroes to die for something worthier than their lives.

If wine is to withdraw its most poetic countenance, the sun of the white dinner-cloth, a deity to be invoked by two or three, all fervent, hushing their talk, degusting tenderly, and storing reminiscences-for a bottle of good wine, like a good act, shines ever in the retrospect-if wine is to desert us, go thy ways, old Jack!

A good conscience is eight parts of courage.

People trifle with love. Now, I deny that love is a strong passion. Fear is the strong passion; it is with fear that you must trifle, if you wish to taste the intensest joys of living.

Each generation is a filter, a sieve; good genes tend to fall through the sieve into the next generation; bad genes tend to end up in bodies that die young or without reproducing.

If we want to postulate a deity capable of engineering all the organized complexity in the world, either instantaneously or by guiding evolution, that deity must have been vastly complex in the first place. The creationist, whether a naive Bible-thumper or an educated bishop, simply postulates an already existing being of prodigious intelligence and complexity. If we are going to allow ourselves the luxury of postulating organized complexity without offering an explanation, we might as well make a job of it and simply postulate the existence of life as we know it!

It is a very helpful insight to say we are vehicles for our DNA, we are hosts for DNA parasites which are our genes. Those are insights which help us to understand an aspect of life. But it's emotive to say, that's all there is to it, we might as well give up going to Shakespeare plays and give up listening to music and things, because that's got nothing to do with it. That's an entirely different subject.

The patient typically finds himself impelled by some deep, inner conviction that something is true, or right, or virtuous: a conviction that doesn't seem to owe anything to evidence or reason, but which, nevertheless, he feels as totally compelling and convincing. We doctors refer to such a belief as "faith".

Orb webs in real life do their business largely in two dimensions. If the mesh is too coarse, flies pass straight through. If the mesh is too fine, rival spiders will achieve nearly the same result at less cost in silk, and will therefore leave behind more progeny to carry on their economically more prudent genes. Natural selection finds the efficient compromise.

Most of what we strive for in our modern life uses the apparatus of goal seeking that was originally set up to seek goals in the state of nature.

I have just discovered that without her father's consent this sweet, trusting, gullible six-year-old is being sent, for weekly instruction, to a Roman Catholic nun. What chance has she?

It's been suggested that if the super-naturalists really had the powers they claim, they'd win the lottery every week. I prefer to point out that they could also win a Nobel Prize for discovering fundamental physical forces hitherto unknown to science. Either way, why are they wasting their talents doing party turns on television?By all means let's be open-minded, but not so open-minded that our brains drop out.

The river of my title is a river of DNA, and it flows through time, not space. It is a river of information, not a river of bones and tissues.

There is no general reason to expect evolution to be progressive - even in the weak, value-neutral sense. There will be times when increased size of some organ is favoured and other times when decreased size is favoured. Most of the time, average-sized individuals will be favoured in the population and both extremes will be penalised. During these times the population exhibits evolutionary stasis (i.e., no change) with respect to the factor being measured. If we had a complete fossil record and looked for trends in some particular dimension, such as leg length, we would expect to see periods of no change alternating with fitful continuations or reversals in direction - like a weathervane in changeable, gusty weather.

I don't want to sound callous. I mean, even if I have nothing to offer, that doesn't matter, because that still doesn't mean that what anybody else has to offer therefore has to be true.

If you have a faith, it is statistically overwhelmingly likely that it is the same faith as your parents and grandparents had. No doubt soaring cathedrals, stirring music, moving stories and parables, help a bit. But by far the most important variable determining your religion is the accident of birth. The convictions that you so passionately believe would have been a completely different, and largely contradictory, set of convictions, if only you had happened to be born in a different place. Epidemiology, not evidence.

In fact writing a computer program is a pretty good way to summarize knowledge about any set of rules.

I think it is not helpful to apply Darwinian language too widely. Conquest of nation by nation is too distant for Darwinian explanations to be helpful. Darwinism is the differential survival of self-replicating genes in a gene pool, usually as manifested by individual behaviour, morphology, and phenotypes. Group selection of any kind is not Darwinism as Darwin understood it nor as I understand it. There is a very vague analogy between group selection and conquest of a nation by another nation, but I don't think it's a very helpful analogy. So I would prefer not to invoke Darwinian language for that kind of historical interpretation.

With so many mind-bytes to be downloaded, so many mental codons to be replicated, it is no wonder that child brains are gullible, open to almost any suggestion, vulnerable to subversion, easy prey to Moonies, Scientologists and nuns. Like immune-deficient patients, children are wide open to mental infections that adults might brush off without effort.

How do we account for the current paranormal vogue in the popular media? Perhaps it has something to do with the millennium - in which case it's depressing to realise that the millennium is still three years away.

There is no spirit-driven life force, no throbbing, heaving, pullulating, protoplasmic, mystic jelly. Life is just bytes and bytes and bytes of digital information.

Another force driving progressive evolution is the so-called "arms-race." Prey animals evolve faster running speeds because predators do. Consequently predators have to evolve even faster running speeds, and so on, in an escalating spiral. Such arms races probably account for the spectacularly advanced engineering of eyes, ears, brains, bat "radar" and all the other high-tech weaponry that animals display.

For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.

When the ricochets of atomic billiards chance to put together an object that has a certain, seemingly innocent property, something momentous happens in the universe. That property is an ability to self-replicate; that is, the object is able to use the surrounding materials to make exact copies of itself, including replicas of such minor flaws in copying as may occasionally arise. What will follow from this singular occurrence, anywhere in the universe, is Darwinian selection and hence the baroque extravaganza that, on this planet, we call life. Never were so many facts explained by so few assumptions. Not only does the Darwinian theory command superabundant power to explain. Its economy in doing so has a sinewy elegance, a poetic beauty that outclasses even the most haunting of the world's origin myths. 

Natural selection is an extremely simple process, in the sense that very little machinery needs to be set up in order for it to work. Of course the effects and consequences of natural selection are complex in the extreme. But in order to set natural selection going on a real planet, all that is required is the existence of inherited information.

There's nothing nonsensical about saying that what would evolve if Darwinian selection has its head is something that you don't want to happen. And I could easily imagine trying to go against Darwinism.

Think about the two qualities that a virus, or any sort of parasitic replicator, demands of a friendly medium, the two qualities that make cellular machinery so friendly towards parasitic DNA, and that make computers so friendly towards computer viruses. These qualities are, firstly, a readiness to replicate information accurately, perhaps with some mistakes that are subsequently reproduced accurately; and, secondly, a readiness to obey instructions encoded in the information so replicated.

The popularity of the paranormal, oddly enough, might even be grounds for encouragement. I think that the appetite for mystery, the enthusiasm for that which we do not understand, is healthy and to be fostered. It is the same appetite which drives the best of true science, and it is an appetite which true science is best qualified to satisfy.