Reply to Objection 2: That which is desired, though really future, is, nevertheless, in a way, present, inasmuch as it is hoped for. Or we may say that although the desired good itself is future, yet the hindrance is reckoned as present, and so gives rise to sorrow.
Reply to Objection 3: Desire gives pleasure, so long as there is hope of obtaining that which is desired. But, when hope is removed through the presence of an obstacle, desire causes sorrow.
Whether the craving for unity is a cause of sorrow?
Objection 1: It would seem that the craving for unity is not a cause of sorrow. For the Philosopher says (Ethic. x, 3) that "this opinion," which held repletion to be the cause of pleasure, and division [*Aristotle wrote , 'want'; St. Thomas, in the Latin version, read 'incisionem'; should he have read 'indigentiam'?], the cause of sorrow, "seems to have originated in pains and pleasures connected with food." But not every pleasure or sorrow is of this kind. Therefore the craving for unity is not the universal cause of sorrow; since repletion pertains to unity, and division is the cause of multitude.
Objection 2: Further, every separation is opposed to unity. If therefore sorrow were caused by a craving for unity, no separation would be pleasant: and this is clearly untrue as regards the separation of whatever is superfluous.
Objection 3: Further, for the same reason we desire the conjunction of good and the removal of evil. But as conjunction regards unity, since it is a kind of union; so separation is contrary to unity. Therefore the craving for unity should not be reckoned, rather than the craving for separation, as causing sorrow.
On the contrary, Augustine says (De Lib. Arb. iii, 23), that "from the pain that dumb animals feel, it is quite evident how their souls desire unity, in ruling and quickening their bodies. For what else is pain but a feeling of impatience of division or corruption?"
I answer that, Forasmuch as the desire or craving for good is reckoned as a cause of sorrow, so must a craving for unity, and love, be accounted as causing sorrow. Because the good of each thing consists in a certain unity, inasmuch as each thing has, united in itself, the elements of which its perfection consists: wherefore the Platonists held that "one" is a principle, just as "good" is. Hence everything naturally desires unity, just as it desires goodness: and therefore, just as love or desire for good is a cause of sorrow, so also is the love or craving for unity.
Reply to Objection 1: Not every kind of union causes perfect goodness, but only that on which the perfect being of a thing depends. Hence neither does the desire of any kind of unity cause pain or sorrow, as some have maintained: whose opinion is refuted by the Philosopher from the fact that repletion is not always pleasant; for instance, when a man has eaten to repletion, he takes no further pleasure in eating; because repletion or union of this kind, is repugnant rather than conducive to perfect being. Consequently sorrow is caused by the craving, not for any kind of unity, but for that unity in which the perfection of nature consists.
Reply to Objection 2: Separation can be pleasant, either because it removes something contrary to a thing's perfection, or because it has some union connected with it, such as union of the sense to its object.
Reply to Objection 3: Separation from things hurtful and corruptive is desired, in so far as they destroy the unity which is due. Wherefore the desire for such like separation is not the first cause of sorrow, whereas the craving for unity is.
Whether an irresistible power is a cause of sorrow?
Objection 1: It would seem that a greater power should not be reckoned a cause of sorrow. For that which is in the power of the agent is not present but future. But sorrow is for present evil. Therefore a greater power is not a cause of sorrow.
Objection 2: Further, hurt inflicted is the cause of sorrow. But hurt can be inflicted even by a lesser power. Therefore a greater power should not be reckoned as a cause of sorrow.
Objection 3: Further, the interior inclinations of the soul are the causes of the movements of appetite. But a greater power is something external. Therefore it should not be reckoned as a cause of sorrow.
On the contrary, Augustine says (De Nat. Boni xx): "Sorrow in the soul is caused by the will resisting a stronger power: while pain in the body is caused by sense resisting a stronger body."
I answer that, As stated above (A[1]), a present evil, is cause of sorrow or pain, by way of object. Therefore that which is the cause of the evil being present, should be reckoned as causing pain or sorrow. Now it is evident that it is contrary to the inclination of the appetite to be united with a present evil: and whatever is contrary to a thing's inclination does not happen to it save by the action of something stronger. Wherefore Augustine reckons a greater power as being the cause of sorrow.
But it must be noted that if the stronger power goes so far as to transform the contrary inclination into its own inclination there will be no longer repugnance or violence: thus if a stronger agent, by its action on a heavy body, deprives it of its downward tendency, its consequent upward tendency is not violent but natural to it.
Accordingly if some greater power prevail so far as to take away from the will or the sensitive appetite, their respective inclinations, pain or sorrow will not result therefrom; such is the result only when the contrary inclination of the appetite remains. And hence Augustine says (De Nat. Boni xx) that sorrow is caused by the will "resisting a stronger power": for were it not to resist, but to yield by consenting, the result would be not sorrow but pleasure.
Reply to Objection 1: A greater power causes sorrow, as acting not potentially but actually, i.e. by causing the actual presence of the corruptive evil.
Reply to Objection 2: Nothing hinders a power which is not simply greater, from being greater in some respect: and accordingly it is able to inflict some harm. But if it be nowise stronger, it can do no harm at all: wherefore it cannot bring about that which causes sorrow.
Reply to Objection 3: External agents can be the causes of appetitive movements, in so far as they cause the presence of the object: and it is thus that a greater power is reckoned to be the cause of sorrow.