Look into understandable matters

The mind’s keenness should be turned entirely to the smallest and most easily understandable matters, and to dwell on them longer until we become accustomed to discern truth distinctly and clearly.

After explaining the two operations of our intellect, intuition and deduction, which we said should alone be used for acquiring knowledge, we proceed in this and the following proposition to explain with what diligence we can become more suitable for exercising them, and at the same time cultivate two principal faculties of the mind, namely perspicacity, by distinctly intuiting individual things, and sagacity, by artfully deducing one thing from another.

Indeed, how the intuition of the mind should be used, we know from the very comparison of the eyes. For whoever wishes to look at many objects at the same time with the same glance sees none of them distinctly; and similarly, he who is accustomed to attend to many things at once in a single act of thought has a confused mind. But those craftsmen who are engaged in minute works and are accustomed to direct the eye attentively to each point acquire the capacity by practice to perfectly distinguish things however minute and subtle they may be; so too those who never distract their thoughts with various objects but always occupy themselves with considering each simplest and easiest thing become perspicacious.

It is a common fault of mortals to regard as more beautiful those things which are difficult; and most people think they know nothing when they see a very clear and simple cause of something, while they admire lofty and deeply sought-after reasonings of philosophers, even if these mostly rest on foundations that have never been sufficiently examined by anyone, certainly not in good health who hold darkness more dear than light. But it must be noted that those who truly know recognize truth with equal ease, whether they have derived it from a simple subject or from an obscure one: for they grasp each with a similar, unique, and distinct act, once they have arrived at it; but there is an entire diversity in the path, which certainly must be longer if it leads to truth from the most remote and most absolute principles.

Therefore, everyone must accustom themselves to embrace as few and as simple things as possible in thought, so that they never think they know anything unless they see it as distinctly as they see that which they know most distinctly of all. Indeed, some are born more suitable for this than others, but minds can also be made far more suitable for this by skill and exercise; and there is one thing which seems to me above all to be particularly admonished here, namely that everyone firmly persuade themselves that sciences, no matter how hidden, must be deduced not from great and obscure things, but only from easy and more obvious ones.

For example, if I wish to examine whether any natural power can pass in the same instant to a distant place and through the whole medium, I do not immediately turn my mind to the force of a magnet or the influences of the stars, nor even to the speed of light, but I reflect on the local motions of bodies, because nothing in this whole category can be more perceptible. And I observe that a stone cannot move from one place to another in an instant, because it is a body; but a power similar to that which moves the stone can only be communicated in an instant, if it passes from one subject to another without any body, as in the case of a stick, if I move one end of a very long stick, I easily conceive the power by which that part of the stick is moved, necessarily moving at the same time all its other parts, because then it is communicated without a body, such as a stone from which it is carried.

Similarly, if I want to know how from one and the same simple cause contrary effects can be produced simultaneously, I will not borrow from physicians medicines that expel certain humors and retain others, nor will I consult fortune-tellers about the moon, that it warms through light and cools through some hidden quality; but I will rather look at a balance, in which the same weight at one and the same instant raises one end of the beam while depressing the other, and the like.