It will be commodious here to know that (as before has been said) although every motion of the kernel, seen to have been joined by nature to each of our thoughts even from the beginning of our life, they may yet be annexed to others by habits, as experience shows in words that excite motions in the kernel, which according to the institution of nature represent only to the soul their sound, when they are pronounced by the will; or by the figure of their letters when they are written and which yet never the less by a habit acquired by thinking what they signify, as soon as ever their sound is heard, or their letters seen, use to make us conceive the signification rather then the form of our letters or the sound of their syllables. It is also convenient to know that although the motions, as well of the kernel as the spirits and brain, which represent certain objects to the soul, be naturally joined with those that excite certain passions in her, yet they may by habit be separated, and annexed to others very different; and moreover that this habit may be acquired by one action only, and requires not a long usage. As when a man at unawares meets with any nasty thing in a dish of meat which he has a very good stomach to, this accident may so alter the disposition of the brain, that a man shall never afterwards see any such kind of meat without loathing, whereas before he took delight in eating it. The very same thing may be seen in beasts, for although they have no reason, nor it may be any thought, all the motions of the spirits and the kernel, which excite passions in us, yet are in them, and serve to foment and fortify (not as in us the passions but) the motions of the nerves and muscles their concomitants. So when a dog sees a partridge, he is naturally inclined to run to it and when he hears a piece go off, this noise incites him naturally to run away. Yet nevertheless, we ordinarily breed up spaniels so, that the fight of a partridge makes them couch and the noise of a discharged piece makes them run to it. Now these things are profitable to know, to encourage every one to study the regulation of his passions. For since with a little art the motions of the brain in beasts who are void of reason may be altered, it is evident they may more easily in men and that even those who have the weakest souls, may acquire a most absolute empire over all their passions, if art and industry be used to manage and govern them.