Accordingly, since, in the movements of the appetite, sorrow is a kind of flight or withdrawal, while pleasure is a kind of pursuit or approach; just as pleasure regards first the good possessed, as its proper object, so sorrow regards the evil that is present.  On the other hand love, which is the cause of pleasure and sorrow, regards good rather than evil:  and therefore, forasmuch as the object is the cause of a passion, the present evil is more properly the cause of sorrow or pain, than the good which is lost.

Reply Obj. 1:  The loss itself of good is apprehended as an evil, just as the loss of evil is apprehended as a good:  and in this sense Augustine says that pain results from the loss of temporal goods.

Reply Obj. 2:  Pleasure and its contrary pain have the same object, but under contrary aspects:  because if the presence of a particular thing be the object of pleasure, the absence of that same thing is the object of sorrow.  Now one contrary includes the privation of the other, as stated in Metaph. x, 4:  and consequently sorrow in respect of one contrary is, in a way, directed to the same thing under a contrary aspect.

Reply Obj. 3:  When many movements arise from one cause, it does not follow that they all regard chiefly that which the cause regards chiefly, but only the first of them.  And each of the others regards chiefly that which is suitable to it according to its own nature. ________________________

SECOND ARTICLE [I-II, Q. 36, Art. 2]

Whether Desire Is a Cause of Sorrow?

Objection 1:  It would seem that desire is not a cause of pain or sorrow.  Because sorrow of itself regards evil, as stated above (A. 1):  whereas desire is a movement of the appetite towards good.  Now movement towards one contrary is not a cause of movement towards the other contrary.  Therefore desire is not a cause of pain.

Obj. 2:  Further, pain, according to Damascene (De Fide Orth. ii, 12), is caused by something present; whereas the object of desire is something future.  Therefore desire is not a cause of pain.

Obj. 3:  Further, that which is pleasant in itself is not a cause of pain.  But desire is pleasant in itself, as the Philosopher says (Rhet. i, 11).  Therefore desire is not a cause of pain or sorrow.

On the contrary, Augustine says (Enchiridion xxiv):  “When ignorance of things necessary to be done, and desire of things hurtful, found their way in:  error and pain stole an entrance in their company.”  But ignorance is the cause of error.  Therefore desire is a cause of sorrow.

I answer that, Sorrow is a movement of the animal appetite.  Now, as stated above (A. 1), the appetitive movement is likened to the natural appetite; a likeness, that may be assigned to a twofold cause; one, on the part of the end, the other, on the part of the principle of movement.  Thus, on the part of the end, the cause of a heavy body’s downward movement is the lower place; while the principle of that movement is a natural inclination resulting from gravity.