"Never let yourself be diverted, either by what you wish to believe, or what you think could have beneficent social effects if it were believed; but look only and solely at what are the facts."
"La Ciencia en ningún momento está totalmente en lo cierto, pero rara vez está completamente equivocada y tiene en general mayores posibilidades de estar en lo cierto que las teorías no científicas."
"There are two motives for reading a book; one, that you enjoy it; the other, that you can boast about it."
"Do not fear to be eccentric in opinion, for every opinion now accepted was once eccentric."
"To like many people spontaneously and without effort is perhaps the greatest of all sources of personal happiness."
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts."