Curiouser and curiouser!

When I believed the Non-Reductionist View, I also cared more about my inevitable death. After my death, there will [be] no one living who will be me. I can now redescribe this fact. Though there will later be many experiences, none of these experiences will be connected to my present experiences by chains of such direct connections ….  My death will break the more direct relations between my present experiences and future experiences, but it will not break various other relations. This is all there is to the fact that there will be no one living who will be me. Now that I have seen this, my death seems to me less bad…. When I review the arguments for this belief, and reconvince myself, this for a while stuns my natural concern for the future…. Thinking hard about these arguments removes the glass wall between me and others. And, as I have said, I care less about my death. … Can this matter all that much?

Derek Parfit, Reasons and Persons
Religious suffering is, at one and the same time, the expression of real suffering and protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people. The abolition of religion as the illusory happiness of the people is the demand for their real happiness. To call on them to give up their illusions about their condition is to call on them to give up a condition that requires illusions. The criticism of religion is, therefore, in embryo, the criticism of that vale of tears of which religion is the halo. Criticism has plucked the imaginary flowers on the chain not in order that man shall continue to bear that chain without fantasy or conclusion, but so that he shall throw off the chain and pluck the living flower.

Karl Marx, A Contribution to the Critique of Hegel's Philosophy of Right
Ignorance more frequently begets confidence than does knowledge: It is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.

Charles Darwin, The Decent of Man
We must, however, acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system — with all these exalted powers — Man still bears in his bodily frame the indelible stamp of his lowly origin.

Charles Darwin, The Decent of Man
Questions of ultimate ends are not amenable to direct proof. Whatever can be proved to be good, must be so by being shown to be a means to something admitted to be good without proof. The medical art is proved to be good by its conducing to health; but how is it possible to prove that health is good? The art of music is good, for the reason, among others, that it produces pleasure; but what proof is it possible to give that pleasure is good? 

John Stuart Mill, Utilitarianism
Our moral faculty….is a branch of our reason, not of our sensitive faculty; and must be looked to for the abstract doctrines of morality, not for perception of it in the concrete.

John Stuart Mill, Utilitarianism
The creed which accepts as the foundation of morals, Utility, or the Greatest Happiness Principle, holds that actions are right in proportion as they tend to promote happiness, wrong as they tend to produce the reverse of happiness. By happiness is intended pleasure, and the absence of pain; by unhappiness, pain, and the privation of pleasure. To give a clear view of the moral standard set up by the theory, much more requires to be said; in particular, what things it includes in the ideas of pain and pleasure; and to what extent this is left an open question. But these supplementary explanations do not affect the theory of life on which this theory of morality is grounded - namely, that pleasure, and freedom from pain, are the only things desirable as ends; and that all desirable things (which are as numerous in the utilitarian as in any other scheme) are desirable either for the pleasure inherent in themselves, or as means to the promotion of pleasure and the prevention of pain.

John Stuart Mill, Utilitarianism
The highest activity a human being can attain is learning for understanding, because to understand is to be free.

Baruch Spinoza
We are going to die, and that makes us the lucky ones. Most people are never going to die because they are never going to be born. The potential people who could have been here in my place but who will in fact never see the light of the day outnumber the sand grains of the Sahara. Certainly those unborn ghosts include greater poets than Keats, scientists greater than Newton. We know this because the set of possible people allowed by our DNA so massively outnumbers the set of actual people. In the teeth of these stupefying odds it is you and I, in our ordinariness, that are here.

Richard Dawkins, Unweaving the Rainbow
The transformation of scientific opinion are developments, advances, not revolutions. A law which was held at first to be universally valid proves to be a special case of a more comprehensive uniformity, or is limited by another law, not discovered till later; a rough approximation to the truth is replaced by a more carefully adapted one, which in turn awaits further perfectioning.

Sigmund Freud, The Future of an Illusion