A smell of petroleum prevails throughout.

Speaking psycho-analytically, it may be laid down that any "great ideal" which people mention with awe is really an excuse for inflicting pain on their enemies. Good wine needs no bush, and good morals need no bated breath.

It is for this reason that rationality is of supreme importance to the well-being of the human species...even more, in those less fortunate times in which it is despised and rejected as the vain dream of men who lack the virility to kill where they cannot agree.

I am not myself in any degree ashamed of having changed my opinions.

Never try to discourage thinking, for you are sure to succeed.

When two men of science disagree, they do not invoke the secular arm; they wait for further evidence to decide the issue, because, as men of science, they know that neither is infallible. But when two theologians differ, since there is no criteria to which either can appeal, there is nothing for it but mutual hatred and an open or covert appeal to force.

Although this may seem a paradox, all exact science is dominated by the idea of approximation. When a man tells you that he knows the exact truth about anything, you are safe in inferring that he is an inexact man. Every careful measurement in science is always given with the probable error ... every observer admits that he is likely wrong, and knows about how much wrong he is likely to be.