What should make you believe is your own assent to yourself, and the constant voice of your reason, not that of others.
If antiquity were the rule of faith then the men of old time had no rule. If general consent, if men had perished....
You may try as you please. You must either believe, or deny, or doubt.
We judge that animals do well what they do. Is there no rule whereby to judge men?
To deny, to believe, and to doubt well are to a man what paces are to a horse.
Memory is necessary for every operation of the reason.
Memory and joy are feelings, and even mathematical propositions become so, for reason makes what is felt natural, and natural feelings are effaced by reason.
All our reasoning is reduced to yielding to feeling.
But fancy is like yet contrary to feeling, so that we cannot distinguish between these contraries. One man says that my feeling is fancy, another that his fancy is feeling. We must have a rule. Reason offers herself, but she is pliable in all directions, and so there is no rule.
Reason commands us much more imperiously than a master, for in disobeying the one we are unhappy, and in disobeying the other we are fools.
When we are accustomed to use bad reasons for proving natural effects, we do not wish to receive good reasons even when they are discovered. An example may be taken from the circulation of the blood, to give a reason why the vein swells below the ligature.
We are usually better persuaded by reasons which we have ourselves discovered, than by those which have come into the mind of others.
M. de Roannez said: "Reasons come afterwards, but at first a thing pleases or shocks me, without my knowing the reason, and yet it displeased me for the reason which I only discover later." But I believe, not that he was displeased for those reasons which he afterwards discovered, but that those reasons were only discovered because the thing was displeasing.
_The difference between the mathematical mind and the practical mind._--In the one the premisses are palpable, but removed from ordinary use, so that from want of habit it is difficult to look in that direction, but if we take the trouble to look, the premisses are fully visible, and we must have a totally incorrect mind if we draw wrong inferences from premisses so plain that it is scarce possible they should escape our notice.