Part 86

You may try as you please. You must either believe, or deny, or doubt.

Have we then no rule?

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.

But in the practical mind the premisses are taken from use and wont, and are before the eyes of every body. We have only to look that way, there is no difficulty in seeing them; it is only a question of good eyesight, but it must be good, for the premisses are so numerous and so subtle, that it is scarce possible but that some escape us. Now the omission of one premiss leads to error, thus we must have very clear sight to see all the premisses, and then an accurate mind not to draw false conclusions from known premisses.

All mathematicians would then be practical if they were clear-sighted, for they do not reason incorrectly on premisses known to them. And practical men would be mathematicians if they could turn their eyes to the premisses of mathematics to which they are unaccustomed.

The reason therefore that some practical men are not mathematical is that they cannot at all turn their attention to mathematical premisses. But the reason that mathematicians are not practical is that they do not see what is before them, and that, accustomed to the precise and distinct statements of mathematics and not reasoning till they have well examined and arranged their premisses, they are lost in practical life wherein the premisses do not admit of such arrangement, being scarcely seen, indeed they are felt rather than seen, and there is great difficulty in causing them to be felt by those who do not of themselves perceive them. They are so nice and so numerous, that a very delicate and very clear sense is needed to apprehend them, and to judge rightly and justly when they are apprehended, without as a rule being able to demonstrate them in an orderly way as in mathematics; because the premisses are not before us in the same way, and because it would be an infinite matter to undertake. We must see them at once, at one glance, and not by process of reasoning, at least up to a certain degree. And thus it is rare that mathematicians are practical, or that practical men are mathematicians, because mathematicians wish to treat practical life mathematically; and they make themselves ridiculous, wishing to begin by definitions and premisses, a proceeding which this way of reasoning will not bear. The mind does indeed the same thing, but tacitly, naturally and without art, in a way which none can express, and only a few can feel.

Practical minds on the contrary, being thus accustomed to judge at a glance, are amazed when propositions are presented to them of which they understand nothing and the way to which is through sterile definitions and premisses, which they are not accustomed to see thus in detail, and therefore are repelled and disheartened.

But inaccurate minds are never either practical or mathematical. Mathematicians who are only mathematicians have exact minds, provided all things are clearly set before them in definitions and premisses, otherwise they are inaccurate and intolerable, for they are only accurate when the premisses are perfectly clear.

And practical men, who are only practical, cannot have the patience to condescend to first principles of things speculative and abstract, which they have never seen in the world, and to which they are wholly unaccustomed.

There are various kinds of good sense, there are some who judge correctly in a certain order of things, and are lost in others.

Some are able to draw conclusions well from a few premisses, and this shows a penetrative intellect.

Others draw conclusions well where there are many premisses.

For instance, the first easily understand the laws of hydrostatics, where the premisses are few, but the conclusions so nice, that only the greatest penetration can reach them. And these persons would perhaps not necessarily be great mathematicians, because mathematics embrace a great number of premisses, and perhaps a mind may be so formed that it searches with ease a few premisses to the bottom, yet cannot at all comprehend those matters in which there are many premisses.

There are then two kinds of mind, the one able to penetrate vigorously and deeply into the conclusions of certain premisses, and these are minds true and just. The other able to comprehend a great number of premisses without confusion, and these are the minds for mathematics. The one kind has force and exactness, the other capacity. Now the one quality can exist without the other, a mind may be vigorous and narrow, or it may have great range and no strength.

When we do not know the truth of a thing, it is not amiss that there should be a common error to fix the mind of men, as for instance the moon, to which is attributed the change of seasons, the progress of diseases, etc. For the principal malady of man is that restless curiosity about matters which he can not understand, and it is not so bad for him to be mistaken, as to be so idly curious.

The way in which Epictetus, Montaigne, and Salomon de Tultie wrote, is the most usual, the most insinuating, the most easily remembered, and the most often quoted; because it is wholly composed of thoughts which arise out of the ordinary conversations of life. As when a man speaks of the vulgar error that the moon is the cause of all, we never fail to say that Salomon de Tultie says, that when we know not the truth of a matter, it is well there should be a common error, etc; which is the thought above.

To write against those who plunged too deep into science. Descartes.

Descartes.