Objection 1. It would seem that the honest does not differ from the useful and the pleasant. For the honest is "what is desirable for its own sake" [Cicero, De Invent. Rhet. ii, 53. Now pleasure is desired for its own sake, for "it seems ridiculous to ask a man why he wishes to be pleased," as the Philosopher remarks (Ethic. x, 2). Therefore the honest does not differ from the pleasant.
Objection 2. Further, riches are comprised under the head of useful good: for Tully says (De Invent. Rhet. ii, 52): "There is a thing that attracts the desire not by any force of its own, nor by its very nature, but on account of its fruitfulness and utility": and "that is money." Now riches come under the head of honesty, for it is written (Sirach 11:14): "Poverty and riches [honestas] are from God," and (Sirach 13:2): "He shall take a burden upon him that hath fellowship with one more honorable," i.e. richer, "than himself." Therefore the honest differs not from the useful.
Objection 3. Further, Tully proves (De Offic. ii, 3) that nothing can be useful unless it be honest: and Ambrose makes the same statement (De Offic. ii, 6). Therefore the useful differs not from the honest.
On the contrary, Augustine says (83, qu. 30): "The honest is that which is desirable for its own sake: the useful implies reference to something else."
I answer that, The honest concurs in the same subject with the useful and the pleasant, but it differs from them in aspect. For, as stated above (Article 2), a thing is said to be honest, in so far as it has a certain beauty through being regulated by reason. Now whatever is regulated in accordance with reason is naturally becoming to man. Again, it is natural for a thing to take pleasure in that which is becoming to it. Wherefore an honest thing is naturally pleasing to man: and the Philosopher proves this with regard to acts of virtue (Ethic. i, 8). Yet not all that is pleasing is honest, since a thing may be becoming according to the senses, but not according to reason. A pleasing thing of this kind is beside man's reason which perfects his nature. Even virtue itself, which is essentially honest, is referred to something else as its end namely happiness. Accordingly the honest the useful, and the pleasant concur in the one subject.
Nevertheless they differ in aspect. For a thing is said to be honest as having a certain excellence deserving of honor on account of its spiritual beauty: while it is said to be pleasing, as bringing rest to desire, and useful, as referred to something else. The pleasant, however, extends to more things than the useful and the honest: since whatever is useful and honest is pleasing in some respect, whereas the converse does not hold (Ethic. ii, 3).
Reply to Objection 1. A thing is said to be honest, if it is desired for its own sake by the rational appetite, which tends to that which is in accordance with reason: while a thing is said to be pleasant if it is desired for its own sake by the sensitive appetite.
Reply to Objection 2. Riches are denominated honesty according of the opinion of the many who honor wealth: or because they are intended to be the instruments of virtuous deeds, as stated above (1, ad 2).
Reply to Objection 3. Tully and Ambrose mean to say that nothing incompatible with honesty can be simply and truly useful, since it follows that it is contrary to man's last end, which is a good in accordance with reason; although it may perhaps be useful in some respect, with regard to a particular end. But they do not mean to say that every useful thing as such may be classed among those that are honest.
Source: Summa Theologica (New Advent)