And it is only in the repugnance of those motions, which the body by its spirits, and the soul by her will, endeavour to excite at the same time in the kernel, that all the contestations which use[d] to be imagined between the inferior part of the soul called sensitive and the superior which is reasonable, or else between the natural appetites and the will, consist. For there is in us but one soul only and this soul has no diversity of parts in it; the same which is sensible is rational, and all her appetites are her wills. The error committed in making her act two several parts, which are usually contrary one to another, proceeds merely hence, that her functions have not been distinguished from them [sic] of the body, to which only all that can be observed in us repugnant to our reason ought to be attributed so that there is here no other contestation, unless that the little kernel in the middle of the brain, being driven on one side by the soul, and on the other by the animal spirits (which are only bodies, as I laid down before) it happens oftentimes that these two impulsions are contrary and that the strongest hinders the operation of the other. Now we may distinguish two sorts of motion excited by the spirits in the kernel: some represented to the soul the objects which move the senses, or the impressions found in the brain, which use not any violence on the will; others do use violence, to wit, such as cause the passions, or motions of the body concomitant with them. And for the first though they often times hinder the action of the soul, or else be hindered by it, yet by reason that they are not directly contrary, there is not any contestation observed in them. It is only taken notice of among the last, and the wills which resist them. For example, between that violence wherewith the spirits drive the kernel to cause in the soul a desire of anything and that wherewith the soul beats it back by the will she has to avoid the same thing. And what chiefly makes this contestation appear is that the will, having not the power to excite the passions directly (as has been already said), is constrained to use art and fall on considering successively divers things, if but one whereof chance to be strong enough to alter the course of the spirits one moment, it is possible that which follows is not and so the others may immediately resume it again, because the disposition preceding in the nerves, heart and blood is not changed which makes the soul feel herself instigated almost in the same instant to desire and not desire the very same thing. From hence it was that occasion was taken to imagine two contesting powers in her. Yet there may some kind of contestation be conceived herein, that oft times the same cause which excites some passion in the soul excites also certain motions in the body whereunto the soul contributes not and which she stops or strives to stop as soon as ever she perceives them. As is then tried, when that which excited fearfulness causes also the spirits to enter into the muscles, that serve to stir the legs to run away and the will to be bold, stops them.