P60: A Desire arising from either a Joy or a Sadness related to one, or several, but not to all parts of the Body, has no regard for the advantage of the whole man.

Dem.: Suppose, for example, that part A of the Body is so strengthened by the force of some external cause that it prevails over the others (by P6). This part will not, on that account, strive to lose its powers so that the other parts of the body may fulfill their function. For {if it did}, it would have to have a force, or power, of losing its own powers, which (by IIIP6) is absurd. Therefore, that part will strive, and consequently (by IIIP7 and P12), the Mind also will strive, to preserve that state. And so the Desire that arises from such an affect of Joy does not have regard to the whole.

If, on the other hand, it is supposed that part A is restrained so that the others prevail, it is demonstrated in the same way that the Desire which arises from Sadness also does not have regard to the whole, q.e.d.

Schol.: Therefore, since Joy is generally (by P44 S) related to one part of the body, for the most part we desire to preserve our being without regard to our health as a whole. To this we may add that the Desires by which we are most bound (by P9 C) have regard only to the present and not to the future.